|Spoiler Alert: This page contains spoilers. Read at your own risk.|
Kuroba Ayako (黒羽 亜夜子) is a member of the Kuroba Family, a branch family of the Yotsuba Clan. She is also a second cousin to the Shiba siblings. Excluding the short cameo during the Reminiscence Chapter, she first appears in Volume 11 as Yotsuba Maya's representative during her talk with Colonel Balance and another time when facing Kudou Retsu.
Appearance and Personality
On her younger self's brief appearance in Volume 8 of the light novel, Miyuki described her as someone whose dress was abundantly adorned with ribbons, trims, and decorative buttons. Even her above knee socks had ruffles with ribbons on them. Her hair is prettily arranged in curls, and a fringe had been added to her hair band.
For some unconfirmed reason (presumably for Tatsuya's affection and her brothers' clan successor candidate issue), Ayako is said to have a blatant rivalry against Miyuki. She takes great pleasure in making Miyuki displeased, for instance stating the fact that her magic abilities can aid Tatsuya with the information gained by her.
On the twins' brief appearance, Ayako had exhibited an attitude slightly akin to tsundere  characteristics. And, like her twin, she is someone who has taken a liking towards Tatsuya despite his position in the family.
Fulfilling the duty as a member of Kuroba family of Yotsuba which acts as the intelligence network branch of the clan, Ayako herself has a calm demeanor and high skills in handling negotiation or other official duty from Yotsuba as shown in the series. She is quite charismatic and able to make the other side flustered by her words and demeanor alone.
Ayako was born in June 2080 and is the daughter of Kuroba Mitsugu, Yotsuba Maya's cousin.
The Kuroba are in charge of Yotsuba Family's Intelligence. Ayako appeared as a messenger of the Yotsuba Family for a few times in the Visitor Arc.
Relationship with the Shiba Siblings
Childhood (Mentioned in the Steeplechase Arc)
Tatsuya was the one who taught Ayako to use her Perfect Diffusion magic, which he taught her while he was still undergoing training at the Yotsuba main house in elementary school. He had already mastered Decomposition and Self- Restoration magics and was completing his training along with the adults. It was usual practice for a Kuroba Magician to spar with him. So he showed to Ayako, who at the time still did not know her own innate spell and was undergoing training with her father's lackey, an easily comprehensible demonstration of Decomposition.
He knew from his *Elemental Sight* that she possessed a similar magic special ability as his own. And so a still-young Tatsuya, intending to make his own ally and friend, showed to Ayako how to cast a variant of Perfect Diffusion which was based from his own Decomposition.
Ayako's Perfect Diffusion used now was similar to what Tatsuya had taught to her. And because of Tatsuya, it's no overstatement that she established her name, Kuroba Ayako, among the Yotsuba Magicians.
Therefore Ayako never looked down on Tatsuya as a mere Guardian. At the same time, this became one of the reasons for the Kuroba twins to overestimate him.
Unlike the other members of the Yotsuba, she views Tatsuya as someone worthy of her respect and admiration. She was excited to see him and rushed over to him. She dislikes that her father views Tatsuya as only a mere Guardian and not as his relative.
She has a strong sense of rivalry with Miyuki.
Double Seven Arc
Ayako was happy to see Tatsuya, referring to him as "Tatsuya-san". She seems to know him quite well, enough so to know about his rather twisted thought process. She wished to chat casually with him, but was cut short. She was incredibly pleased when he praised her.
Her sense of rivalry with Miyuki has continued.
In order to establish the fact that the twins and the Shiba siblings were complete strangers, they introduced themselves publicly, calling him "Shiba-senpai" and asking for guidance for Magic Engineering later in order to set up an excuse to meet.
She ignored Miyuki when introducing herself to Tatsuya. They obviously ignored each other.
Yotsuba Inheritance Arc
Ayako walked out from the family gathering after Maya announced the engagement between Tatsuya and Miyuki.
She suspects that Maya is using Miyuki to free Tatsuya from the guardian role.
As a member of the Yotsuba Family and the twin sister of one of the candidates to become the next head, she is incredibly skilled in the use of magic. Her strength lies not in the activation speed, or power of her Zone Interference, but in the scale and range of her spell. It is because of this power that she is able to use her signature spells and consider herself (and to be considered) a rival to Miyuki. Her magics are more suitable for intelligence gathering.
Like Miyuki and most powerful modern Magicians, Ayako is presumably talented in all forms of Systematic Magic. Ayako specializes in Convergence-Type and Dispersion-Type Magic.
- Perfect Diffusion (aka Perfect Darkness)
|“|| Ayako had a forte -- the unique magic [Perfect Diffusion], aka [PD (Perfect Darkness)]. A magic that leveled out the target area's gaseous, fluid, and physical energy distributions to the point of non-detection. Categorically [PD] belonged to convergence-type magic. Since it could be recorded into an activation sequence it means it was a normal magic. However, it was safe to say that ordinary magicians could only use [PD]'s weaker version [Diffusion] with difficulty. Tatsuya knew only Ayako could cast [PD].
For example, if sound is to be [leveled off], both voice and music will be totally leveled off into white noise where it's impossible to decode their meanings. However, the sound, in other words the generated sound itself, could not be hidden. This is still on the level of [Diffusion].
When a sound-deadening leveling-off zone has been spread out, the [Diffusion] magic finally becomes [PD]. Ayako's magic activation speed and interference strength were inferior compared to Miyuki's. However, she could spread out event interference zones larger than Miyuki's, and for this it was praised as the Yotsuba's greatest ability.
It's on dimly-lit outdoors at night where Ayako can fully unleash her specialty. She can selectively and instantaneously level off her own or her allies' reflection and emitted electromagnetic waves, melding into the darkness. By leveling off audio waves and air current variations, she can evade auditory and olfactory detection. And so she assimilated them into the night. Her code-name [Yoru] was based on one character of her first name, and at the same time it designated her unique perfect diffusion magic.
- A simple, yet multi-system spell that utilizes Weight-Type, two layers of Convergence-Type, and Move-Type Magic. This spell removes an object’s inertia (including the human body), surrounds it with a cocoon of air, and creates an even larger tunnel of vacuum around it to move the object through that tunnel. Despite the multi-system nature of this technique, it only uses four basic processes and isn't too much of a complicated spell. There are some disadvantages, however, as the users needs to scout out the destination prior to forming the surrounding air currents that buffered the tunnel of vacuum. If someone had the ability to repeatedly leap into the air while using this ability, they might even be able to continuously use this ability to confuse their opponent. However, this technique was fundamentally incompatible with attacking and was more suited for fleeing.
|“||Ayako’s specialized magic was ‘Ultimate Scattering’, a convergence type magic that diffused vapor, energy, etc. evenly to the point where they could barely be recognized anymore, The Ultimate Scatter spell had no direct relationship with Mirage Bat. However, Ayako had another magic which was just as much a specialty of hers as ‘Ultimate Scattering’.||”|
- Anti-Object Physical Barrier - Even though, her barrier is a single layer anti-object barrier, it has more than sufficient strength to withstand a barrage of bullets from High Powered Rifles.
Head Mount Display
This is an "eye patch"-like item that is actually an HMD (Head Mount Display) and that Ayako wears on some of her missions. The exact functions of this head mount display are unknown, but the HMD appears important enough for Ayako to wear it even though it causes her some discomfort.