Sailor Suit And Machine Gun - Graduation

18-year-old high school girl Izumi once inherited leadership of a four-man yakuza gang, the Medaka Group. The group disbanded after a failed raid on the rival Hamaguchi gang. With graduation coming up, Izumi resumed her life as a high school student.

When her friends are caught in a scam by a fake modeling agency, and a dangerous new drug called 'Cookie' turns up at her school, Izumi investigates. When she questions the Hamaguchi boss, he in turn suspects the Medaka of drug dealing. Are the authorities trying to clean up the town by provoking a turf war?