The Neighbor No. Thirteen
The Neighbour No. 13' (Rinjin 13-go) is a horror genre film, released in December 2005. It was directed by Yasuo Inoue, written by Santa Inoue and Hajime Kado, and starred Oguri Shun and Nakamura Shido.
Summary
The Neighbour No. 13 is about a peaceful, young man named Murasaki Juzo who had been horribly bullied as a child, from eating bugs to having acid poured down his mouth, leaving him traumatized. Now he's older and just go a new job at a construction company. Unfortunately, he finds out his boss is the kid who used to bully him, and what's worse is that his boss had just moved into the apartment above him. His boss doesn't remember who Juzo is, but it seems his bullying ways have not faded away. He constantly picks on Juzo at work. All the pent up anger inside of Juzo manifests itself into 13 -- Juzo's other self. It seems that Juzo has been a schizophrenic for some time now, but nothing really happened until his childhood traumatizer kicked the switch. Now 13 is going around eliminating anyone and everyone around him.