As a child he joined a karate dojo, but years later he was forced to quit by his parents who wanted to prepare him for junior high school. He and Madoka Tokumaru, who once worked part-time at the dojo, work to resolve the conflict. During that phase, Shunpei confesses that he admires Tokumaru, despite his previous, contradicting actions, and works to strive for the goal of beating him. In "Yume Musubi, Koi Musubi", Shunpei speaks of an unrequited love, which is revealed to be Tokumaru in "Koi Cha No Osahou". Unfortunately, he got turned down after confessing, but still continues to attend the dojo and stay by Tokumarus side.