Draw your weapons and take aim, because Sabagebu! is coming at you!
Momoka Sonokawa was just minding her own business on the train one day when she encountered a pervert. Before she could do anything about it, a girl named Miou appears, brandishing two pistols and and scaring him off, only to be arrested herself a few minutes later for possessing firearms.
Later Momoka sees this same girl at her school and follows her to a run down building. It turns out Miou is the president of the school's Survival Game Club, and it doesn't take long for Miou to capture Momoka and force her into joining them.
Over the course of the series, Momoka and her new "friends" will take part in multiple battles against enemies from other schools, a rival from the same school who wants to see the club shut down and even each other (on multiple occasions). With friends and classmates like these, will Momoka even make it to graduation?