Hotaru Tachibana, a high schooler with a fierce sense of justice who is constantly mistaken for a boy, storms off to confront a host who swindled a classmate — only to find the con man is her new neighbor, Masamune Matsuoka. He settles the dispute with toy guns, and after losing badly Hotaru is pulled into the world of survival games. She joins Masamune's Toy Gun Gun team and sets her sights on the national tournament, despite being a terrible shot.