German Plus Ame (2007)

This wild and outrageous Japanese film by Satoko Yokohama tells the story of a 16 year old girl named Yoshiko, who lives all alone since her mother died and father entered the hospital. There isn't much opportunity in a small town for a teenage girl to make a living, so Yoshiko gives recorder lessons to the neighborhood kids - but when she learns that some of her pupils have caught the eye of a local pedophile, she takes up a part-time job as a vigilante! Her plans to do right by her odd array of students include brutal emasculation, but at the end of the day, the sweet young thing never forgets to reward her precious tykes with treats.