As Mari and Kouzuki Yuki are working at their part-time job in Akihabara to earn money for a buzzer set, Shiki and Inoue arrive in the area to train themselves with a quiz bowl game in the arcade. They're battling against a player called "Second Lieutenant Chisato" when Ashiya shows up, and the pair finds out that their opponent is someone they know quite well. Then a strange, somewhat suspicious character approaches the group...