I'd like to see a festival chapter. It's probably going to have to be a festival from a place further from their town so they don't get found out. A beach chapter is going to be more likely given both Kaoruko and Rintaro mention the beach, and that would be great too.
I think this is Rintaro's cue to ask Kaoruko when's her birthday. It would be weird if he knew her birthday and suddenly gave her a gift or something without her telling him when.