Don't Cry, Tokyo

Don't Cry, Tokyo is a horror anime film directed by Satoko Samo

Plot
A high school in Tokyo, a bullied 18-year old girl named Mai Yokogata discovers a ghost of an 18-year old Japanese soldier named Yoshihiro Tsumi who used to attend the school she is in who was killed in the Battle of Indonesia, who cries in the upstairs boy's bathroom and kills anyone who enters, and she befriends the spirit, and he begins killing her bullies and tormenters in horrible ways when they encounter him