Mumei was walking around the Red and White teams to check which of her senpais have tails. She also didn't run the relay because she was supposed to have left before that event.
Come to think of it, did anyone who said they might leave halfway actually leave?
Regarding the IRyS/Kronii rrat, IRyS does seem to go out of her way to banter with Kronii and Kronii usually reciprocates. Plenty of quotes to take out of context.
Calli's twerking is infectious (although the moment IRyS sees AZKi watching she gets embarrassed)
Since no one said it yet, RIP Iofi (top right)
