Gyo Ichinomiya, a sergeant of the Ichinomiya Group, a large zaibatsu, has lived his whole life under the strict instruction of his father, “Never owe a debt to another person. One day, a girl named Nino, who claims to be a Venusian, saves his life when he meets her on a bridge on the Arakawa River. Unintentionally answering “yes,” Gyoko retreats under the Arakawa bridge, where strange people are living.