Shuuji is Harima Kenji's younger brother, though they do not live together. He first appears at the Tsukamoto doorstep as a runaway child, but in reality, he had become infatuated with Tsukamoto Yakumo and wanted to get close to her. While staying there, he plays several games with Tenma, all of which he wins. Later, Tenma calls on Yakumo to challenge Shuuji at Go, a game he does not know how to play.
After this incident, Shuuji assists Harima by dressing up as animals to help protect them, pretending to rehearse a play. More recently, he attended the Cultural Festival with Tennouji Mio. Shuuji and Mio attend the same school, and although he has feelings for Yakumo, he genuinely cares for Mio as well, showing concern when she got lost during the Cultural Festival.
Shuuji and Yakumo represent the Go Faction, and his initial attraction to Yakumo was so strong that he ran away from home just to be near her.
