Recca Hanabishi is a high schooler obsessed with ninja who insists he is one himself, and he has vowed to serve as ninja to anyone who can beat him. Everything changes when he meets classmate Yanagi Sakoshita, whose touch heals any wound, and a woman calling herself Kage Houshi attacks him to force out the flame he carries in his right hand. Pledging himself to Yanagi instead, Recca is drawn into a hidden world of ninja clans and the mystical weapons called madougu.