Seiji appears in Gyre, Part 1. Seiji's family was badly affected by the tsunami, and in the hopes of earning the money to help them out, he attempts to beat the world record for bouncing a soccer ball (which is 24 hours). His feat makes him a media sensation, but ends up dropping the ball at six hours after being distracted by the loud footsteps of his father. In a fit of rage, he kicks the soccer ball but ends up breaking the sword holder for Tatsoro's katana. Seiji bows to his father and apologizes to him for breaking it, but they are soon interrupted by clapping outside. Wade (The man who Kazuko made a friendship with during the tsunami) found Tatsoro's katana and was returning it back. Kazuko thanks Seiji because if he hadn't attempted to break a world record, the family would have never been on the news and they would have never found the katana. Tatsoro bows to Seiji in happiness.