Mild-mannered Shizuya Kondo lives a normal life, occupied with his dreary office job as a women's underwear designer. But, he also happens to be the only son of the leader of the biggest criminal organization in the Kanto region... and when his father is murdered by a rival gang, Shizuya is forced to become the new head of his yakuza family! Working as a businessman by day and a yakuza boss by night, Shizuya finally begins to realize his true potential. But, things take an unexpected turn when Akemi, his secret office-crush, is suddenly kidnapped.

A demonic reincarnation of a Japanese general from the 10th century appears in the early 20th century Tokyo with a mission to destroy the blooming city.