Izumi Hoshi is a senior in high school, but she led a small yakuza group in her past. After killing her uncle's murderer with a machine gun, her yakuza group disbanded. Izumi now lives an ordinary life as a high school student and works as a manager at a cafe. A dangerous situation soon awaits Izumi. ~~ Adapted from the novel series "Sailor Suit and Machine Gun" (セーラー服と機関銃) by Akagawa Jiro (赤川次郎).