セーラー服と機関銃

A high school girl becomes a yakuza clan leader! An eternal bestseller! Hoshi Izumi, a pretty high school girl whose father has just been killed, is forced to succeed him as leader of the run-down, four-member Medaka clan. Immediately after she assumes the title, a machine gun is fired into the clan's office, and the curtain has already risen on this tumultuous drama!

(Translator: DeepL (with edits by @meagstudies))