Natsuki and Yuuko are insistent that Riko practice kissing before actually kissing her boyfriend at the Summer Festival.
It wasn't just Kumiko and Reina growing closer at the festival with yuri undertones. Ah. Riko says no!
Yuuko and Natsuki get serious and work together pretty well. Even Riko can't believe how someone else's first kiss is such a big deal to them.
Riko kept trying to escape whenever Natsuki and Yuuko devolved back to their normal bickering, but that first kiss was strong enough to keep reuniting them.
So, where was Gouto in all this? Uh oh! They saw him leaning in toward another girl! Unforgiveable! No worries. It was his sister and she delivered the punchline that's going to be the hallmark of all these specials "What is this?" which is what Taki-sensei first said when he heard the terrible music the band first made.