Gojo is able to complete the Black Lobelia and Black Lily cosplays thanks to Marin's help. Both Marin and Sajuna try on their cosplays and they're both excited about how nicely they turned out, and Marin is even more excited about their upcoming group cosplay. When the day finally arrives, Marin and Sajuna get an unexpected visitor.

Summer vacation is coming to a close. Wakana received an SOS from Marin, who hadn't finished her homework, so he ended up helping her study at her house. They later realize that Marin had forgotten some math drills at school, so they go to get them. While alone at the school, Marin and Wakana make plans to go to a summer festival together. And when that day finally arrived...