Yura Yamato is a shy girl who enrolls in Stella Women's Academy. On her first day at the academy, she checks into her dorm to find that her roommate, third year Sonora Kashima is out visiting her family. Looking around the room, she discovers her roommate's collection of military items, such as guns, action guerilla movies etc. At the same time, the C3 Club meets elsewhere in school to discuss the recruitment of new students into the club. After coming up with a ridiculous plan and deciding that it would be unrealistic, they decided to take a break and play a Rambo-style battle to lighten the mood. Rento goes to Yura and Sonora's room to borrow Sonora's M60 and unexpectedly stumbles onto Yura playing with the "props" while watching Rambo. Deciding that yura fulfilled the condition to be recruited, she brought Yura to the C3 Club.

With the club holding back on sweets to save for an upcoming 24 hour tournament, Sonora suggests they raise the money for the tournament by holding a stand at the school fair so that they can happily buy sweets with their own funds. However, this turns out to be a crayfish-related disaster, and they are soon left with no money for either. Deciding to work with what they've got, they decide to put on a cosplay shooting café, with Sonora managing to borrow a portable shooting range. As the festival gets underway, the club is visited by Karira's twin brother, Aira, who is from Seikou Academy's opera club, also planning to enter the 24hr tournament. In order to draw in more customers, Honoka puts together a bikini water pistol fight display. When it is Yura and Sonora's turn to duel, Yura ends up landing a hit on Sonora whilst she was distracted by a kid bumping into Rento.