Kamui 神威 is a member of the Yato Tribe 夜兎族 and the son of Umibouzu 星海坊主, older brother of Kagura 神楽 and Housen 鳳仙's pupil. His excellent fight skills helped him become Captain of the 7th Division of Harusame's Thunder Guns 春雨の雷槍, the most powerful combat unit within the Harusame 春雨 group and Overlord of Yoshiwara. Since defecting from the Harusame, he no longer holds these positions.
Like his sister, Kamui has blue eyes and red hair, albeit his reaches his lower back and always tied. He wears a traditional uniform used in Chinese martial arts, with a black top, which sleeves reach his elbows, and a beige bottom that reaches the middle of his lower leg.
Kamui firmly believes that the Yato are to remain on the battlefield and shows his disapproval of Housen staying locked up in Yoshiwara. Because of this belief, he shows no pity towards family or subordinates as a sign of weakness is unacceptable. He tried to revive the abandoned tradition of a Yato clansmen killing their own parent to pove their strength, although failed to successfully execute it.
Despite this, he pays respect to the opponents he kills by sending them off with a smile. He also, by his own words, doesn't kill children and dislikes killing women.
Kamui used to be Housen's pupil and live with his parents and younger sister. At one point, however, he attempted to kill his father, Umibouzu, to prove his strength. After failing and having his life spared because of Kagura's plea, he left his home.
He first appears in Yoshiwara, where he arrived wishing to meet the woman who made his master "weak". To do so, he kidnaps Seita just as he and the Yorozuya were being shown a route out of Yoshiwara to use as a bargaining chip. Even with Seita there, Kamui and Housen begin to fight much to the dismay of Abuto 阿伏兎 and Ungyou 云業's opposition. At the end, the fight is interrupted at the cost of Ungyou's life and Abuto's left arm.
Kamui then searches for and finds Seita, who escaped during the commotion, and leads him to Hinowa's chamber. After both Housen and Sakata Gintoki 坂田 銀時 also arrive and begin to fight, Kamui sits at the sidelines and watches, impressed by Gintoki power. He takes credit for Housen's death and so is appointed as Yoshiwara's new Overlord. He has no interest in the city, however, and became its ruler solely to prevent anyone from getting close to Gintoki.
Later, Kamui is tricked by the Harusame into thinking they were going to eliminate Takasugi Shinsuke 高杉 晋助's Kiheitai 鬼兵隊 and Takasugi himself, when the actual target was Kamui himself. At the execution, Takasugi volunteeres to strike Kamui down only to instead free him from his bonds. The Kiheitai and now-former 7th Division then both assault the Harusame ship, overwhelming the space pirates. Kamui and Takasugi then leave for Earth together.
- Kamui's hair was actually black in a flashback in Episode 42 of the Gintama anime, and also in an ending before the Yoshiwara is Burning arc. After the ending credits of Episode 146, Ginpachi-sensei answered a fan letter about Kamui's black hair by throwing it in the Rejection Box.