The episode begins at Kawagoe Private Academy, where the choir is preparing for the All-Japan High School Boys Choir Competition in the Kanto Division. The choir director, Haruo Hibiki, is focused on selecting the competition piece, while the students are distracted by the upcoming Kawagoe Summer Festival.

At this festival, the choir hopes to witness a performance by Urawa Academy, last year's national champions. It also marks a reunion for Tenshi, nicknamed Cardbocchi, and his old friend Juu-kun from Urawa Academy. They reminisce about their past, which is weighed down by a missed opportunity from their childhood.

Meanwhile, Haruo Hibiki, known for his eccentric behavior, interrupts a taiko drum performance at the festival and insists on correcting their rhythm and technique. This intervention leads to a humorous and unexpected collaboration between the choir and the taiko drummers.

The episode takes a personal turn when Shizuo, a choir member, is confronted by his father, who had hoped Shizuo would join his bodybuilding club. A heartfelt conversation unfolds, revealing the father's loneliness since Shizuo stopped training with him. This moment of understanding strengthens the bond between Shizuo and his father and inspires the choir's competition piece.

The episode ends with the choir members returning from the festival more united and inspired. Tenshi decides to apologize to Juu-kun for their past misunderstanding. The choir is now more determined than ever to shine at the upcoming competition with a newfound sense of camaraderie and purpose.