By every report, junior high student Seigi seems ordinary except for his exceptional martial arts talent and a urge to defend the vulnerable. Yet when he tests this altruism by rescuing an elderly homeless man from a group of street thugs, the enigmatic figure expresses thanks by… etching a tattoo onto Seigi"s palm! The mark proves to be an ancient, powerful weapon coveted by all—including a fierce heroine bearing her own ink. With his life hanging in the balance and no single skill enough to face superpowered adversaries, can Seigi awaken his tattoo"s hidden strength and survive for another fight in the face of imminent danger and the world around him?
