This was probably the young Hiroko Yakushimaru's most successful role in what was then the beginning of her career. She plays Koizumi, a high school student (hence the sailor suit part of the title) whose father passes away and by virtue of bloodline becomes the leader of a small Yakuza gang. The movie has some comic moments just from the concept, that a girl could run this somewhat motley group of guys. However, it is Miss Yakushimaru's performance that really makes this film. One moment sh'e weak, the next strong, one minute playful, the next serious, one minute a girl, next on the cusp of womanhood. One of the things I like about this film was they didn't complicate it by giving her a love interest. She gets to make mistakes, be tough and be a female in a male dominated world without there being too much reference to her attractiveness. Miss Yakushimaru has since gone on to make other films, including playing the wife in the two excellent Always Sunset On Third Street films, but this is her more or less at the beginning. I think you'll like it.
Review of Sailor Suit and Machine Gun
