Yahiko is a descendant of a samurai. His father died during the Battle of Ueno in the Boshin War, killed at the Keneiji Temple. His mother passed away from syphilis in a brothel shortly after giving birth to him, having worked there to provide food for them. Initially, Yahiko was coerced into thievery by the local Yakuza, who deceived him into thinking he still owed them money they had supposedly given to his mother for medicine.
With the assistance of Himura Kenshin and Kamiya Kaoru, Yahiko becomes an apprentice of the Kamiya Kasshin-Ryuu style. He has a friend and rival named Tsukayama Yutarou and a sweetheart, Sanjou Tsubame, who works at the Akabeko restaurant.
