Shunichi Domoto is a talented and athletic fifth‑grade boy who routinely helps his school’s sports teams. When his friend Beso’s yo‑yo is stolen by the school bully Benkei, Shunichi challenges Benkei to a duel to recover it. After defeating Benkei, he encounters the exceptionally gifted yo‑yoer Seito Hojoin, who humiliates him for mocking the game. Determined to avenge his loss, Shunichi enters Japan’s national yo‑yo championship, where he develops new techniques and faces formidable rivals.