The residents of the lab throw a party to celebrate the end of the semester and play their traditional party game where they recite Prime numbers. Kanade has never studied Prime numbers so Himuro explains their scientific significance, and even that one of mathematics greatest unsolved problems, the Riemann hypothesis, involves Prime numbers. Himuro gets drunk and starts acting very clingy around Yukimura, while Kosuke strangely does the same with Ibarada...