Years ago, the death of the infamous Enma Syndicate's chairman, who united all those below him, led to numerous individual yakuza groups being created. These groups are filled with "ayashimon"—supernatural creatures possessing various powers—who now lurk in the shadows of modern-day Japan.

Maruo Kaidou, inspired by his favorite manga heroes, has spent the majority of his life ruthlessly training. He has become so strong that no business will hire him and no martial arts organization will accept him. But just as Maruo reaches his wit's end, he encounters a young girl named Urara, a yakuza head fleeing from an enemy group.

Though Urara tries to chase him away because of his status as a regular human being, Maruo jumps at the thought of an exciting fight. Now in the midst of a new world filled with individuals wielding powerful abilities, Maruo feels that he cannot return to his old, boring life. Thus, he decides to join Urara's yakuza group—becoming its very first member.