Enzai: Falsely Accused [OVA] 4w5e1k

The protagonist is Guys, a young boy from a poor family, who gets caught for stealing candy from a Paris store. And of course he will be investigated and punished. 4u1p4p

However, after being railroaded by a city detective named Guildias, Guys finds himself accused, convicted, and sentenced to life imprisonment for the murder of a man he never met.

From that point on, most Enzai takes place inside a dark, claustrophobic, dirty prison, in there, Guys experiences humiliation and torture of various kinds, much of it involving sexual acts such as rape and forcible sodomy.