|Spoiler Alert: This page contains spoilers. Read at your own risk.|
The Yotsuba (四葉, よつば, lit. four leaves) Clan is one of the two most influential and strongest houses in the Ten Master Clans. Bearing the number Four (四) in their name, it is a clan where its members' lives are shrouded in secrecy. The current Head of the Yotsuba Clan, Yotsuba Maya, the next heir of the Yotsuba Clan, Shiba Miyuki and Shiba Tatsuya being her fiancé were the only recognized official members of Yotsuba known to the world.
Despite the system of checks and balances to prevent the possibility of Magicians losing control of themselves, placed by the creation of the Ten Master Clans, the Yotsuba Clan is gradually becoming too powerful, even among the powerful Ten Master Clans. With Shiba Miyuki, Shiba Tatsuya, and Yotsuba Maya existing in the same family at the same time, it is believed that the Yotsuba may become an existence that will eclipse the Ten Master Clans. Their ever-growing power and influence have caused other Ten Master Clans to be wary of their growth and status to the point that some of the other Family's are trying to weaken them by any means possible.
The Yotsuba have grown too powerful. They have long surpassed the Ten Master Clans and are beginning to upset the balance of the country. 
When these two(Tatsuya & Miyuki) individuals become the center of the Yotsuba Family, the other 27 Houses constituting the Ten Master Clans-18 Assistant Houses might become useless in terms of suppressing the Yotsuba Family, even as a group.
In the policy of independence if portrayed positively, or the policy of self-centeredness if portrayed negatively that the Yotsuba adopted (though, the independence doesn’t originally have a bad meaning), they had always adopted the stance of not caring about what the other Houses do. Solidly progressing towards improving their own efficiency, ranked with the Saegusa in the top of the Ten Master Clans only by the virtue of their magic power, it was a clan which can be said to be heretical even among the Ten Master Clans.
Currently, the magic group with the most power in Japan isn’t the Nation Defense Force, but actually the Yotsuba Family. The existence of the Yotsuba Family lay in the entirely opposite direction. Right now (at least for now), they were subservient to the Japanese government, but if they suddenly morphed into terrorists, they were held as individuals who could pull the trigger on World War IV. On the magic side, for such a zealous organization, they were not raised up as something worthy of respect, but of complete and utter fear. 
Despite their limited numbers, they were more than capable of becoming the counter-terrorism trump card and carrying out actions that went beyond the reach of the law that the government needed. In terms of black ops and assassinations, none among the “Numbered Families” could match the Yotsuba Family 
- 1 Background
- 2 Area of Influence
- 3 Secrecy
- 4 Village
- 5 Members
- 6 Guardian System
- 7 Servants
- 8 Business Ventures
- 9 Secret Techniques/Unique Magic
- 10 Random
- 11 The Senate
- 12 Trivia
- 13 References
The Yotsuba Family was not a family with a very long tradition. The family was only formed by Maya’s grandfather as the first Head, and Maya was only the Third Family Head.
The Yotsuba and the unique magic they possess originated from the Fourth Institute, the laboratory that created them and is now controlled by them. Their ancestors were magicians with strong mind-manipulation abilities that were selected and gathered together by the Fourth Institute in order to be strengthened and have their primary field of their Magic Calculation Area directly modified as part of their research focusing on "endowment and improvement of magical abilities given by the mind's structure for the usage of Mind Manipulation Magic." 
The "Yotsuba" that was produced at that time inevitably descended from two types of magician lineages. The first lineage was one where a person was born with a Mind Manipulation Magic that was strengthened. The other lineage was one where a person was born with a Magic Calculation Area that is warped by a strong power. These two heritages stand side by side and mix to form the Yotsuba known today. Even those who share the same blood display the two traits randomly. For example, Shiba Miya inherited the traits of the former with Mind Structure Manipulation, a form of Mind Manipulation Magic that only she can use; Maya represents the latter, as she did not acquire any form of Mind Manipulation Magic, but instead a distinctive power from birth.  As for Shiba Miyuki, it seems that she possessed both traits in her power as shown from her abilities of Cocytus, Niflheim, Inferno, and etc.
The Yotsuba Clan is the only family in the Ten Master Clans and 18 Assistant Houses that originated from the Fourth Magic Institute. There are other family's which have the Number 'Four' in their name, such as ‘Yomo’, ‘Shihoudou’, and ‘Watanuki’ but they don't belong to the 28 Houses. 
The Yotsuba is sponsored by a hidden Sponsor who holds considerable influence over the Fourth Research Institute to this day, and whose intentions and requests are regarded highly by Yotsuba Maya and Hayama. 
|“||"I know what you want to say, Hayama-san. I have no intention of causing discord. I only do this because I believe that obtaining a 'Parasite' is necessary for the Yotsuba."
"Does Madam believe then that studying the Parasite, will bring us closer to the mysteries of Mental Interference?"
"Yes. Just what exactly is the mind, is a question the Yotsuba has been endlessly pursuing. It's said that the Parasites are individual mental information bodies. Information on substance, structure, location......even if only a little, it should give us hints as to the true nature of the mind."
—Conversation between Maya & Hayama
Even though Yotsuba clan is widely known (and feared) for their combat capabilities, they were also a clan of magic researchers, who seek and explore the possibilities of magic. Answer the question "what is the mind/soul?", that is the purpose of their research, which the other Master Clans don't know about.
Area of Influence
The Yotsuba Clan's influence encompasses specifically the Tōkai region and both the Gifu and Nagano prefectures. During the Master Clans Conference held every four years, the Head of the Yotsuba Clan gives a report on the status of the regions it monitors. 
The Yotsuba's influence throughout Japan is powerful and vast enough to allow the Clan to systematically alter every personal database at the civilian level, a feat that requires exceptional clearance at the highest level, which showcases how their influence is deep enough to intervene even at the highest level of government. 
Maya visited “The Sponsor” Aoba. It is revealed that their relationship is not either party absolutely relying on the other. Aoba was the previous owner of 4th Research Institute until the National Defense Force robbed the facility from Aoba. Yotsuba rebelling and taking over at least indicates they are on good terms. While Yotsuba from time to time relies on Aoba’s privileges, Aoba sometimes relies on Yotsuba’s strength. Basically, they rely on each other. Yotsuba is not the only family produced by the 4th Institute. Before it was called the 4th, they magician development and mating were already ongoing. Even now, Aoba sometimes provides Yotsuba with “blood”. The previous version of 4th institute basically existed long before all other numbered research institutes.
It was noted that the Yotsuba only use their power from personal connections, only for self-defense and retribution. It seems that they have no lust for power. 
|“||“It’s the first time for me in a situation where the target’s whereabouts are unknown, and I say it’s very rare for the Yotsuba. And I haven’t known of one who has the capacity to escape from the Yotsuba’s hand.”||”|
—Conversation about Gu Jie
The Yotsuba Clan keeps itself shrouded in secrecy and out of the public's eye, unlike the Saegusa Family. 
It is greatly implied that due to the extreme secrecy surrounding the Yotsuba Clan, the general public doesn't know which Magicians are connected to the Yotsuba Clan. It is implied that the only publicly known Magician from the Yotsuba Clan is the current head of the Yotsuba Clan; Yotsuba Maya. As of Volume 17, Shiba Miyuki and Shiba Tatsuya had been publicly announced as members of the Yotsuba Clan.
It is strongly implied that most Magicians related to the Yotsuba Clan don't use "Yotsuba" as their family name but instead use other family names in order to disguise their identities. Also, it is implied that when a person becomes the Head of the Yotsuba Clan, their family name would be formally changed to "Yotsuba".
They are using encrypted communication between members of Yotsuba and similar to National Defense, they had a policy of changing encryption code continuously in the one-hour interval.
From a policy of independence if portrayed positively, or the policy of being self-centered, if portrayed negatively that the Yotsuba adopted, they have always adopted the stance of not caring about what other Houses do. It has been stated by Katsuto that because of the high level of secrecy surrounding the Yotsuba, nobody knows what they've done or plan to do. 
"You don't have to be that worried, Miyuki-san. At any rate, we can get a hold of a rough location by foretelling here."
The mountain village where the Yotsuba reside is in a narrow valley not recorded on any map, which is in the old Yamanashi Prefecture that bordered the old Nagano Prefecture.  Due in part to the village not being recorded on any map, it has no designated address for receiving deliveries. The Kobuchizawa Station is the nearest station to the village, for a vehicle to come and pick up visitors. 
The Yotsuba village, once a secret military base, is built to protect their research results by severing external communications in case of an emergency. In such an emergency the village can sustain itself in all aspects. However, the Yotsuba family still have their own enterprise, trade, and sponsors to maintain outside of their village. So the head of the family occasionally leaves the village in person.
There is a tunnel that leads to the entrance of the village. Inside the tunnel are branches of a pathway with a mechanism that needs a flow of Psion waves in a certain waveform at specific points in order to be able to stay on the route which leads to the Yotsuba's Village. The tunnel provided an automatic gate of Non-Systematic Magic. The mechanism essentially cuts off the village from the outside world, by land transportation. This facility is meant to conceal the address of the Old Fourth Research Institute. Due to the high confidentiality of the Old Fourth Research Institute, only the name is known, and the address is not even known to the highest government and military officials. As the Yotsubas had inherited this facility, they went around literally erasing the memory of anyone who knew this secret, completely hiding the location of their home. 
A barrier surrounds the village to repel intruders, and it can easily be decomposed by Tatsuya's Decomposition. The catch is if until the barrier is rebuilt by Magicians with recognition inhibitors, they'd be overworked day and night because doing so isn't a simple task. 
In the center of the village lies a conspicuously large single-story Manor, the Yotsuba Main House. 
In Tokyo, the Yotsuba have a safe and secure residence for Tatsuya and Miyuki to use that was prepared for them. 
They ask Tatsuya and Miyuki if they know exactly where they are at. Miyuki isn't aware but Tatsuya answers that this building must belong to the Yotsuba family. Katsushige nods and says that this is the Yotsuba family's Tokyo headquarters and that this is also a temporary dormitory for combatants of the Yotsuba.
This building was located in the middle of a large undeveloped site. It is not difficult to guess that this site played the role of a "serf trench" and was stuffed with a large number of protective systems.
The office part up to the third floor had absolutely no windows, and its lighting was organized by a fiber-optic structure. Residential areas, located from floors 4 and above, instead of windows, for the most part, had balconies, so it was difficult to see the interior from outside.
Completely covering the top floor and the roof, the protective fence was installed not to protect it from falls, but to protect it from outside penetration. Instead of the blinds on the windows, armor plates may be provided.
The building is very much like a fortress, it is in the middle of a large plot of private land, with a lot of security devices. There are lots of offices without windows, and it also is designed to prevent people from being able to break in from the outside.
The Main House conceals the address of the Old Fourth Research Institute. Due to the high confidentiality of the Old Fourth Research Institute, only the name is known, and the address is not known even to the highest government and military officials. As the Yotsuba Clan had inherited the facility, they went around literally erasing the memory of anyone who knew this secret, completely hiding the location. 
The Main House is a rather large building done in the style of a traditional Samurai residence. A description of an outsider's impression of the Yotsuba Main House as seen from outside of the gate. Compared to a typical residence it is certainly spacious. Even calling it a mansion does not feel like a misnomer. However, someone who looked at the grand mansions of those like the Saegusa Family and Ichijou Family would probably be rather surprised by its simple snug appearance. The Yotsuba do not care about the spaciousness of their house. Because the Yotsuba Clan, who maintain a systematic policy of secrecy, would never invite a large number of outsiders as guests. Perhaps they think a grand mansion would only be an encumbrance. 
In contrast to the Eastern style of architecture for the exterior of the house, the big reception room is done in the Western style. There are even paintings of landscapes adorning the brightly hued walls, not reproductions either; but rather, these were original oil paintings. And the stately natural wood table in the middle of the room could easily seat over ten people. 
The Audience Chamber gives off the impression of emptiness. This was possibly due to the fact that, instead of the space being occupied by the legs of over ten chairs, there are only the four legs of a sofa placed by a table; also, aside from the table and sofa, there are almost no furnishings, which appear to leave all too much space leftover in the room. Making the room feel unnecessarily vast was probably for the purpose of psychologically inducing a feeling of oppression. 
Near the Main House, there is a complex which is the residence of the Kuroba Twins' grandmother, Yotsuba Yume, younger sister of Yotsuba Genzou, Tatsuya and Miyuki’s deceased grandfather, as well as aunt to the current Clan Head, Yotsuba Maya. 
The name Miyakijima [巳 焼 島] was derived from the original name of the neighboring island of Miyakejima [三 宅 島], which was recorded as Goyakidzima [御 焼 島], with the first character [御] replaced by [巳 (snake)], in honor of the year of the snake in which he appeared. It was also sometimes called the "New Island of the 21st Century," because it appeared in the first year of the 21st century.
This entire island is privately owned by the Yotsuba Family, and to be precise it is owned by a real estate company controlled by the Yotsuba, but it’s all the same.
Miyuki used this Miyajima Island as a training ground for the development of the Niflheim casting, that time it only had the prison with some surrounding facilities. However, this island now has an airport, geothermal power plants, Induction stone refinement plant and many miscellaneous facilities. This will also be the site for the E.S.C.A.P.E.S project.
Miyaki Island is a zone that had been used for a prison for criminal magicians until recently, where it was divided into other zones where the construction of magic research facility groups is progressing. The former is on the western coast of the island, the latter is on the north-east coast of the island, and the stellar furnace plant is also under construction on the north-east coast. 
One of the Yotsuba branch families, magicians serving under the Mashiba Family, from the time when the island was a prison they have been in charge of its security and defense. Although they aren't blood-related to the Mashiba Family, the magicians in charge have a proven record for keeping order over the heinous criminals that are imprisoned. 
This reminds Tatsuya of Maya's plan to start building the necessary facilities for the family to be able to live on the island if necessary.
Based on the fact that they possess unique abilities unmatched by other families and have a select few but extremely powerful group of Magicians, the Yotsuba Clan is a special entity within the Ten Master Clans. 
Unlike other families that possess similar magic that is inherited through blood relations, the Yotsuba Clan doesn't have Magicians that possess similar abilities, but instead unique ones. 
While possessing an aptitude for having Mental Interference Magic is an important quality for the Yotsuba Clan Head to have, it isn't an absolute condition. Up to the previous Clan Head, Yotsuba Eisaku, he was highly versatile in Mental Interference Magic, but Miya who had the powerful ‘Mental Design Interference’ Magic hadn't been selected to be the next Clan Head, instead, Maya was chosen. 
The Yotsuba Clan currently possesses one of the strongest Magicians in the modern era. Yotsuba Maya is known throughout the world as the "Demon Lord of the Far East", the "Midnight Queen", and is the current Head of the Yotsuba Clan. 
|“||When the two individuals (Tatsuya & Miyuki) become the center of the Yotsuba Family, while Maya still lives, the other 27 Houses constituting the Ten Master Clans - 18 Assistant Houses might become useless in terms of suppressing the Yotsuba Family, even as a group.||”|
—Conversation between Kudou Retsu and Kazama
The 28 Houses were originally conceived to be Side Branches that stem from the development of Magicians, however, the Yotsuba Clan are the only ones to have adopted a Side Branch System. 
- Yotsuba (Head Family)
Shiiba, Mashiba, Shibata, Kuroba, Mugura, Tsukuba, Shizuka. Among those, Shiiba, Mashiba, Shibata the easiest to understand. Each of them ‘four-leaf’, which is a variation of ‘Yotsuba’.
it’s an open secret (widespread rumor) that the Kuroba is related to the Yotsuba Family. The Kuroba family was a branch family of the Yotsuba clan that gathered intelligence. They did not limit themselves to magical means; they used a variety of information gathering methods such as wiretapping, hacking, and traditional human investigation and had a trump card for secret intelligence activities that allowed them to read the Psion information body recorded in a corpse: "Memory of the Dead".
Maya asked Tatsuya if other people can also use the magic, Gatekeeper, which neutralizes other magicians. Tatsuya says after alteration, magicians with adequate aptitude in mental interference can in principle use it. Maya asked if it has been codified. Tatsuya replied he has brought it. Maya asks if it is possible to let the Tsukuba Family further develop it. Tatsuya does not mind it.
The reason why he had called Yuuka was that he felt that the Tsukuba Family, who were skilled in Mental Interference magic, were better equipped to track down the enemy than the Kuroba Family for this case.
|“||In regards to the secret feud between the Yotsuba and Dahan; on the Yotsuba side, there were thirty dead. From this war, the Yotsuba lost the head of the Clan and half of its fighting strength. On the other side, Dahan's dead were approximately four thousand. For the sacrifice of a mere thirty people, the Yotsuba Clan assassinated four thousand: cabinet ministers, high-class bureaucrats, officers, magicians, and researchers; as for the continent of Asia, it had all its research results on modern magic annihilated.
Due to this damage, Dahan suffered an internal collapse after one year and the Great Asian Union unified the continent of Asia. As for East Asia, the antagonism between the North and the South came to a resolution; as for the northern hemisphere, a resolution for the worldwide border conflicts was jury-rigged. It was the end of World War III. And among those who knew the truth about the collapse of Dahan, the Yotsuba were feared as "Untouchable".
The name "Untouchables" started to spread 30 years go after the destruction of Dahan. "Do not touch Japan's Yotsuba. If you lay your hands on them, you will be destroyed."
James recollected all the incidents caused by the Yotsuba and the rumors that had spread that it was due to the Yotsuba that the Great Asian Union were forced into peace negotiations with Japan. Also, the strategic class magic that was used on the southern tip of the Korean Peninsula was rumored to been developed by the Yotsuba.
Tatsuya did not think that the Yotsuba Family would respect such sentiment. After all, the Yotsuba was a clan that waged war against one nation for kidnapping a certain girl, fulfilling their revenge in exchange for half of their family members being killed. So it's reasonable for such personal memory sentimentalism to exist within the Yotsuba, or rather it fitted them very well.
For the sake of one girl, they declared war on a whole country, and took revenge at the cost of half the family's lives. In a family-like Yotsuba, the sentimentality, in which personal memories are carefully preserved, was important (or, I might say, appropriate).
“I heard Kudou Retsu was close with the previous head of the Yotsuba, and with that, he was the private teacher of Yotsuba Miya and Yotsuba Maya.”
“The previous head… That was our grandfather, wasn’t it?”
“Yes. The leader of ‘that incident’ when the Yotsuba’s ‘infamy’ was broadcast to the world.”
For some reason, Miyuki smiled a little. When Tatsuya made an “Eh?” expression, she amusingly giggled more and more.
“…Pardon me. Onii-sama has been speaking as if it was other people’s problem.”
Tatsuya furrowed his brows in doubt.
“What do you mean by that?”
“Come on, Onii-sama. If the world knew of the truth behind ‘Scorched Halloween’, they would be too busy to even think what Grandfather had done, right?”
Even if the opponent be a nation, or the world, he would protect us, the Yotsuba Family from an unreasonable fate, the owner of absolute power. The strongest magician who would have the power to destroy the world as an individual. We wanted to create such a transcendental person as a magician of the Yotsuba in the future.
The whole family was obsessed with such a superhuman desire. The Yotsbua Family as a whole had such a deep superhuman desire, instead of an individual feeling inside.
A demon with the power to destroy the world. That was an existence that we, the Yotsuba Family, prayed for. Our prayer of wishing for the destruction of the world, the symbol of the Sin of the Yotsuba. 
“That is a misunderstanding. We are not a military organization. We certainly earn remuneration for violent acts, but that is just a side job. If I dare to classify it, the Yotsuba Family is a research organization.” “A side job that is feared throughout the whole world, what a joke...”
Elders 長老 (素体)
Great Grandfathers Generation 曾祖父世代 (第四研設立接改姓)
- Yotsuba Kazuma (四葉 和真) - (Deceased)
- Yotsuba Hyouma (四葉 兵馬) - (Deceased)
- Yotsuba Yuuma (四葉 勇魔) - (Deceased)
Grandfathers Generation 祖父世代 (四葉家確立)
- Yotsuba Eisaku (四葉 英作) - (Second Clan Head, Deceased)
- Yotsuba Motosuke (四葉 元輔) - (Deceased)
Parents Generation 父母世代
- Mashiba Shinsuke (真柴 真佐) - (Branch House Head)
- Shiba Tatsurou (司波 龍郎 [旧姓・司馬])
- Shiba Miya (四葉 深夜) - (1st Wife, Deceased)
- Shiba Sayuri (司波 小百合) - (2nd Wife)
- Yotsuba Maya (四葉 真夜) - (Third Clan Head)
- Shiiba Hidetsugu (椎葉 英嗣) - (Branch House Head)
- Shizuka Haruto (静 陽人) - (Branch House Head)
- Shibata Osamu (新発田 理) - (Branch House Head)
- Mugura Asumi (武倉 藍霞) - (Branch House Head)
Candidate Generation 候補世代 (次代当主)
- Shiba Tatsuya (司波 達也) - (Fiancé of the Next Clan Head)
- Shiba Miyuki (司波 深雪) - (Next Clan Head)
- Kuroba Ayako (黒羽 亜夜子)
- Kuroba Fumiya (黒羽 文弥)
- Shibata Katsushige (新発田 勝成)
- Tsukuba Yuuka (津久葉 夕歌)
- Shinonome Yoshimi (東雲 吉見)
The magicians in the Yotsuba Family were actually not many in number. Even not limiting it to only magicians related by blood to the Yotsuba compared to the other 10MC Families like the Saegusa or even Ichijou the number of magicians they could deploy was indeed ‘small’.
Although the number of Yotsuba Magicians was small, they won in terms of ability, these results had been proven. However, there were times where numbers were important, for such cases the Yotsuba had an organized network of disposable outsiders to collaborate with them.
The Yotsuba Family was often asked to purge those who conspired against the nation. To capture rebel organizations or magicians that worked towards that goal. It didn’t mean taking action only on magicians that took direct hostile action against the nation, so long as a magician was aiding a foreign military force with the intent to harm this nation it was enough.
This work had become an important source of income for the Yotsuba Family. Not just financially, Yotsuba's combatants had been trained through this work as well. It was also a means to brainwash the captured rebellious magicians.
They did classic brainwashing to their enemies. Earnestly imprinting the fear of death for defying the Yotsuba. An ideology of fear. In other words, those who weren’t afraid of death couldn’t be affected by this magic. Then, the Yotsuba would offer a deal to those who feared death, 'Depending on your work, we'll let you free.”
Then, those mercenary magician troops undertook missions in order to get their lives as a reward, being used by the Yotsuba in a variety of jobs.
In response to Maya's tragedy, the Yotsuba enacted a policy of attaching guards to Clan Members who possess an especially superior disposition for magic, which is when the Guardians were created. 
The Guardians of the Yotsuba Clan bear the duty of preserving their primary's life even at the cost of their own. This title comes from the combat slaves that once rescued a young woman from the Yotsuba Clan from enemy attack and were responsible for preserving the Yotsuba bloodline. On the surface, this duty differs little from ordinary bodyguards, but temporarily hired bodyguards are fundamentally different from Guardians. While Yotsuba Guardians aren't selected from birth, once selected, their term is for life. Though they were the same as bodyguards in that they serve for 24 hours a day, 7 days a week, Guardians don't possess the right to resign from their duties. Since Guardians are only relieved when their primary is released from protection to this day, without exception, Yotsuba Guardians are done with their duty only until the day they die. 
Guardians receive no monetary rewards. All the living necessities are provided by the Yotsuba. Whenever cash is needed, the Yotsuba supply it. To be correct that is not a reward, it is the cost of maintaining the power of protection. Guardians have no private life of their own. All of them, the male Guardians and the female Guardians, whether they call the one they protect Master or Mistress, are devoted to serving that person. Guardians do not normally use the designations of "Master" or "Mistress" when present within the Clan. 
- Shiba Tatsuya (司波 達也) [Mistress: Shiba Miyuki]
- Only Miyuki can release Tatsuya from his duties as a Guardian, though another Guardian, likely of the same age and gender, would be dispatched to her. Of course, Miyuki hopes to retain Tatsuya as her Guardian for reasons that go beyond her own stubbornness. Within the Yotsuba Clan, a Guardian's duty is of the highest priority. While serving as Miyuki's Guardian, he wouldn't be assigned any meaningless tasks. Nor would he receive any dirty jobs. 
- The Yotsuba Clan hasn't relinquished their hold on Tatsuya. He remains a Yotsuba Guardian. Only under the conditions of his role as a Guardian not being compromised, is he allowed to participate in military missions. Besides guardian responsibilities, the Yotsuba Clan is not allowed to assert their precedence. That is the agreement the National Defense Force 101 Independent Magic-Equipped Battalion has with the Yotsuba Clan. 
Sakura Series (桜・シリーズ)
The Second Generation of the modified “Sakura” Series are born of parents that were genetically engineered to grant them powerful magical abilities. The “Sakura” Series’ specialty is creating heat resistant barriers that repel physical objects. Though its functionality and variability are not on par with the Juumonji Family’s “Phalanx”, judged solely on its utility as a defensive mechanism, Minami was able to match the Juumonji Family's level even at the tender age of 15. 
- Sakurai Honami (桜井 穂波) - (Deceased) [Mistress: Shiba Miya]
- Sakurai Minami (桜井 水波) [Mistress: Shiba Miyuki]
- Chiho Okazaki [Mistress: Tsukuba Yuuka]
- Sakurai Naho (桜井 菜穂)
Minami did not go “In that second!?” in surprise. She had been raised by the Yotsuba as a maid who was a Guardian candidate. She had seen many aberrant people in the Yotsuba training course. Rather her scale of normal was set close to abnormal. For her, Tatsuya’s physical prowess was pretty much in the normal category.
Bard Series (楽師・シリーズ)
The Modified Body ‘Bard Series’ is a group of Magicians who are especially good at Systematic-type Oscillation (Vibration) Magic, especially in interfering with sound waves, and they are Magicians made for combat. However, the tendency of their specialized magic for fighting is different, specifically when it comes to search operations, detecting interference, bewitching and damage mitigation type magic rather than combat magic. 
- Tsutsumi Kotona (堤 琴鳴) [Master: Shibata Katsushige]
- Tsutsumi Kanata (堤 奏太) [Master: Shibata Katsushige]
Within the Yotsuba Family, all of the Butlers were called equally as 'Butler', whether it was Obara or Aoki or Hanabishi or even Hayama, the eight of them, in reality, were in a position to supervise employees in each sector. However, only Hayama was in charge of private (internal) issues out of all eight of the Butlers.
- Hayama Tadanori (葉山 忠教) - (Head Butler/'Senate' Manager)
- Hanabishi Tajima (花菱 但馬) - (2nd Butler/Resource Manager)
- Kurebayashi (紅林) - (3rd Butler/Fourth Institute Manager, General Manager of the Technical Department)
- Aoki (青木) - (4th Butler/Financial Manager)
- Kuroda (黒田) - (5th Butler/Scout Recruiter, Real-estate Manager)
- Mr. Shirakawa (白川) - (6th Butler/Assistant Butler to Hayama)
- Kimura (木村) - (7th Butler/Mayor, Village Real-estate Manager)
- Obara (小原) - (8th Butler/Transportation, Police Riot Manager)
There is known to be at least one lesser butler that works at the Yotsuba Main House. 
There are several maids, though Shirakawa is in-charge of all of them.
- Mrs. Shirakawa (白川) - (Head Maid)
In Japan, there are companies that use "Yotsuba" or "Yatsuha" in their name. The Yatsuha name is associated with the Four Great Systems and Eight Major Types in Modern Magic as well as the Garbhako'sa-Dhatu Mandala, so modern corporations enjoy using the name. Using the name of the Yotsuba Clan from the Ten Master Clans is considered a taboo by individuals affiliated with magic. If Japanese corporations use the Yotsuba name, both intelligence and criminal organizations fear to rouse the Yotsuba Clan's wrath by harming their assets. There are companies that pretend to be affiliated to the Yotsuba Clan, even if they don't say otherwise. 
Four Leaves Technology
- Main Article: Four Leaves Technology FLT, the literal translation is "Four Leaves Technology", although the official company records and brand name intentionally uses only "Four Leaves". It is secretly funded by the Yotsuba Clan and they hold the power of attorney over the stocks that Tatsurou received when Miya died. 
The Yotsuba Clan has hotels in every region throughout Japan that are either under their direct patronage or receive funding from them. The Kuroba Family in particular when due to the nature of their work, they end up going on numerous business trips and use these hotels. 
Secret Techniques/Unique Magic
- The Yotsuba secret technique to cast at fast speeds without the use of a CAD. It is made possible by mentally "carving" the images of the Activation Sequence into memory, allowing the user to recall the Activation Sequence directly from memory instead of a CAD to construct the Magic Sequence of the spell in the Magic Calculation Area of the brain. It can only be used with single systematic spells that are not overly long or complex.
- The ability to transform information into Psion signals and transfer that information through the nervous system and into another person's subconscious Magic Calculation Area through physical contact is unique to the Yotsuba Clan. Ordinary Magicians need to plug in the target data into their Magic Calculation Area when they invoke magic, however, the data is a Magician's perception in digitized form and generally can't be shared. 
This reminded her of Tatsuya's words that if she ever wanted to retire from Stars, to quit as a soldier. That he is convinced that Lina is unsuitable to be a soldier, that she can come to the Yotsuba’s. Lina didn't understand why she was remembering this.
The Senate is an informal secret organization that sponsors the Yotsuba Clan, and in exchange they dispose of magicians that commit violent crimes or magicians that plan to do anything similar. The Yotsuba Clan only cares about The Senate, not the 10 Master Clan, Magic Association nor the Japanese Government. Unless attacked, the Yotsubas tend to ignore the activities of these entities. Hayama is an agent of The Senate, and only the head of the Yotsuba Family will be privy to this information. After spending so many years with Maya, he places more importance on his position as Maya’s butler than as his position in The Senate.
Yakumo reveals to Tatsuya that there is an organization that wants the Parasites expelled from Japan. Yakumo also mentions that Aoba is part of this organization
- The name of the Shiba branch family might be a reference to the now extinct Shiba Clan.
- Both the "Old Yamanashi and Nagano Prefectures", are so-called due to the fact that both prefectures have had towns and villages merge into and out of other prefectures as well.
- The Yotsuba Branch Families have their name either derived from a variation of Yotsuba (四葉, よつば, lit. four-leaves), or derived from name of flowers having four leaves:
- The name Shiiba is derived from a variation of Yotsuba (四葉, よつば, lit. four-leaves).
- The name Mashiba is derived from a variation of Yotsuba (四葉, よつば, lit. four-leaves).
- The name Kuroba is taken from the Japanese phonic pronunciation of the English word four-leaf clover (四葉のクローバー).
- The name Shizuka is taken from a four-leaf Lily Flower, Shizuka was inspired from a plant called Hitorishizuka, (ヒトリシズカ).
- The name Shibata is derived from a variation of Yotsuba (四葉, よつば, lit. four-leaves).
- The name Mugura is taken from a four-leaf Lily Flower, Mugura was inspired from a plant called Yotsubamugura (ョツバムダラ).
- The name Tsukuba is taken from a four-leaf Lily Flower, the Tsukubanesou (衝羽根草).
- Volume 16, Chapter 7
- Volume 12, Chapter 8
- Volume 17, Pg 34
- Volume 17, Pg 234
- Volume 11, Chapter 15.
- Volume 11, Chapter 14
- Volume 16, Pg 101
- Volume 8, Untouchable - The Nightmare of 2062
- Volume 13, The Ten Magician R&D Institutes
- Volume 8, Chapter 10
- Volume 11, Chapter 16
- Volume 30, Chapter 2
- Volume 17, Chapter 5
- Volume 4, Chapter 12
- Volume 13, Chapter 6
- Volume 3, Chapter 6
- Volume 9, Chapter 4
- Volume 12, Prologue
- Volume 16, Chapter 3
- Volume 16, Chapter 5
- Volume 16, Chapter 4
- Volume 15, Chapter 6
- Volume 17, Chapter 1
- Volume 8, Chapter 1
- Volume 8, Chapter 5
- Volume 8, Chapter 3
- Volume 27, Chapter 6
- Volume 16, Chapter 2
- Volume 3, Chapter 4
- Volume 11, Chapter 15
- Volume 20, Chapter 3
- Volume 23, Chapter 3
- Volume 14, Chapter 1
- Volume 16, Pg 172
- Volume 16, Pg 177
- Volume 26, Pg 45
- Volume 6, Chapter 2
- Volume 8, Chapter 2
- Volume 12, Chapter 0
- Volume 25, Chapter 1
- Volume 16, Pg 127
- Volume 8, Chapter 12
- Volume 6, Chapter 3
- Volume 3, Chapter 2
- Volume 14, Chapter 4
- Volume 15, Chapter 1
- Volume 6, Chapter 7
- Volume 32, Chapter 7
- Volume 29,Chapter 14
All items (91)
- Hanabishi Hyougo
- Hashibami Yuki
- Hayama Tadanori
- Mental Design Interference
- Miyaki Island
- Miyaki Island Incident
- Sakura Series
- Sakurai Honami
- Sakurai Minami
- Sakurai Naho
- Shiba Miya
- Shiba Miyuki
- Shiba Tatsurou
- Shiba Tatsuya
- Shibata Katsushige