Oshou Doushin (道信), more commonly known as Kidomaru, was the former champion of the Rengokukan fighting arena, run by the Tendoshu. He used to be a hired killer and was scheduled for execution, but the organisers of the Rengokukan freed him in exchange for fighting in the arena. Outside of the arena, he lived in a run-down temple with his many adopted children.
While in the arena, he wears a disguise themed after an Oni, bearing some similarities such as their red demonic skin and their weapon of choice, a kanabo.
When the Yorozuya come knocking by, he is convinced to stop killing and flee Edo with his children, but is killed in the process by his replacement, Onijishi, member of the Dakini Tribe. His children then convince the Yorozuya to destroy the Rengokukan arena, avenging his death.
His seiyuu also voiced Kuraba Touma, and is also known for voicing Alucard in Hellsing, Giroro in Sgt. Frog, Hody Jones in One Piece, Diethard Reid in Code Geass and Kirei Kotomine in Fate/ Stay Night, among others.