In the beginning of their visit to Minakami High School, the Pop'n Trio expects the entire school might not like them, but that doesn't turn out to be the case as they discover the school's Hero Club. The 5 male members previously had suffered from chuunibyou while the sole female member, Mizuki Hijiri, seems mostly normal, despite being the newest member.

The Pop'n Trio gets interested in the Hero Club once they learn they are an official club, and when the two teams band together to save the world Source: mostly, the school, of course they’ll be prepared for anything!