Terrifying Girls' High School: Lynch Law Classroom (1973)

Three new students at a super-strict girl's school must face off with a repressive school administration, the sadistic, murderous student discipline brigade and corrupt politicians over the murder/suicide of one of their friends. They're approached by a blackmailer (Tsunehiko Watase) who promises to help them exact vengeance in exchange for setting up a corrupt local politician, and aided by a independent Yakuza biker chick (Reiko Ike).