Sabagebu! - Manga

From MangaHelpers: On Sonokawa Momoka's first day of school, she is groped in transit. To her surprise, a girl nearby pulls a gun on the man who grabbed her butt! That incident marks Momoka's first encounter with her new high school's survival game club. Before long, Momoka finds herself reluctantly pushed into joining the club, which is full of cute girls who carry air guns around. The leader, Ootori Miou, is really enthusiastic about her survival skills, and is also surprisingly popular with the girls in the school. Another girl in the club, Kyoudou Maya, is a part-time model. Will Momoka be able and willing to become a valuable member of the survival game club team? [tethysdust]