On her way to the first day at her new high school, Momoka Sonokawa encounters a strange woman who brings a pair of guns out at a train molester, only to get arrested herself for possessing firearms. Momoka spots the same woman at her school and follows her to a dilapidated building, where she ends up being caught by the school's Survival Game Club. Noticing Momoka appears to have a talent for airsoft, the woman, club president Miou Ootori, attempts to recruit her into joining the club, but Momoka flat out refuses...