Do you miss Nemu and Sakura already?
D.C. Onsen is a separate fandisk bishoujo game, where the story seems to be about Suginami inviting Junichi and some girls for some onsen “fun”. This is really a rather short game, and no save/load are possible.
I think you could insert this sidestory around the early stages of the first season. In this game, Nemu doesn’t know about Moe yet. Moe is Mako’s elder sister. Also, the Nemu vs. Sakura fights are still comic and petty, unlike the dramatic stuff of the later episodes.
Well, what else can I say? All the stuff here are typical “onsen” stuff. You know, the baths, the eating, etc. Nemu and Sakura vying for Junichi’s attention especially at dinner time. Some rowdy stuff happen like the rock-paper-scissors strip game between Junichi and Nemu. Ooh…
What I like most (of course) is the Mako part. She gets surprised when she’s been seen window-shopping over those souvenirs. Junichi bought her one, which made her blush a bit. YAY!