From the creator of the School Idol Festival comes a brand new event. The School Idol Showcase! However, only one group per school may enter, meaning that Akihiko's Club and Lanzhu's Clique are far from finished.

After studying in New York for a month, Akihiko Suzuki returns to his School Idol Club only to find it in ruins. During his absence, Lanzhu Zhong and Mia Taylor have brought the School Idol Club to their knees, forming their own 'School Idol Clique'. Will the Nijigasaki High School Idol Club ever become whole again? Or will there be two groups from Nijigasaki standing on the School Idol Festival's main stage to take on Aqours and µ's? It's time for CIVIL WAR.