Ginji the Slasher.

In prison for 50 years after massacring his corrupt workmates with a samurai sword in 1945, Ginji Sonesaki (Riki Takeuchi) is given the nickname of Ginji the Slasher. On his release he finds himself on the streets living with the homeless hiding from a man whose life he tried to end. His former boss and the object of Ginji's hatred is now a highly-regarded figure in politics but Ginji plans to remind him of his past transgressions and make him pay for ruining his life.