Hotaru Tachibana has a strong sense of justice and just cannot help confronting those who choose to perform malicious acts. Furthermore, Hotaru is actually a girl who likes to disguise herself as a boy. After hearing rumors that her best friend was tricked by the popular host of a local club, Hotaru seeks to punish the evildoer. Upon arriving at the club, however, she is challenged to a so-called "survival game" by the host Masamune Matsuoka, where the first person hit by the bullet of a toy gun will lose.