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Saegusa Kouichi (七草 弘一) is the head of the Saegusa family, which is one of the Ten Master Clans. He is the real patron of the National Defense Force Intelligence 3rd Division. Mayumi has referred to him as "Sly Fox".
Appearance & Personality
He is described as a relatively skinny and gentle-looking individual. He looks more like a sharp businessman than a leader.
When he was younger, the Yotsuba and the Saegusa Family's had arranged an engagement between Yotsuba Maya and him, but when he was fourteen and Maya was twelve, she was kidnapped. When she returned, she had lost her emotional connection to Kouichi and her natural ability to reproduce, so the engagement was dissolved. The incident cost him one of his eyes, which he had replaced with a mechanical eye instead of a more natural artificial eye as a reminder of his failure to protect his fiancée. He wears sunglasses both indoors and out to hide the artificial eye. 
It is mentioned that the past discord between Kouichi and Maya makes their relationship very tense and they are now rivals, with Kouichi involved in a plot to undermine the Yotsuba Family and reduce their influence. This may be due to the Saegusa Family leading the Ten Master Clans, and therefore having great influence over the other Families, which is now threatened by the increase in power and influence of the Yotsuba. (Kudou Retsu has stated that, headed by the trio of Tatsuya, Miyuki and Maya, the Yotsuba may be more powerful than the nine other Master Clans combined).
Kouichi hoped to marry Mayumi off to either Juumonji Katsuto or Itsuwa Hirofumi, the heirs to two of the Ten Master Clans, but these plans did not bear fruit. Ichijou Masaki was not considered due to him being too young. During the 10 Master Clans arc, he proposes Mayumi and Tatsuya's engagement.
He is first seen after the events of the Scorched Halloween, where he was talking to Itsuwa Family Members Itsuwa Mio and Itsuwa Hirofumi. They, along with Mayumi, were discussing Mio's deployment by the Japanese government to rattle swords with the Great Asian Union, in order to better negotiate with them.
Nakura Saburou was his right hand and Kouichi often consulted with him.
It has been hinted that his Magic is linked with light, and that he has the ability to instantly burn up a paper card into ashes.
He can also prepare a maximum of up to nine magic sequences, keep them on stand by, and unleash each one of them later at blinding speed similar to the ability of Mitsuya Gen.