Morita leads the high school band Kobijitsu, initially performing acoustic folk music marked by delicate strumming and lyrical themes. The band's name translates to "Ancient Fine Arts," creating a deliberate contrast with the similar name of the film's protagonist trio. When confronted by the delinquent protagonists intending to intimidate over the name conflict, Morita responds by inviting them to hear Kobijitsu's music.

After witnessing the protagonists' raw, rhythmic performance, Morita expresses fervent admiration for its primal energy, declaring it embodies rock and roll's essence. This encounter sparks his radical reinvention of Kobijitsu, shifting their sound from folk to aggressive, full-throttle rock. He subsequently invites the protagonists to join Kobijitsu at a local rock festival.

During the festival, Kobijitsu opens with their new rock direction. Morita’s guitar malfunctions near their set’s conclusion, forcing a dejected exit. Later, the protagonists initiate an impromptu collaborative performance on stage. Morita and his bandmates return to participate, merging their sound seamlessly with the protagonists' band for a unified finale.