Cain's Descendant.

Munakata has an unrelenting guilt from killing his mother when he was 15 years old. After being imprisoned for 10 years, he is released and heads to Yako, a small industrial town, to work as a machinist. Living in a tiny apartment, he is tasked with secretly creating a gun out of an old TV remote control and unknowingly destroys the fragile balance of the town.