Riki-Oh: Toukatsu Jigoku

The events of these anime happen in a prison. Despite being prisoners, the main protagonists in both anime have a strong sense of justice and must fight against evil and corrupt prison officials. 

Both anime have a prison setting, as their protagonists are prisoners. In both anime, the protagonist tries to uncover the corruption of the prison staff. They both have a lot of action and violence, as well as some gory scenes.  

Both '80s OVAs feature a reticent young man with superhuman abilities who graphically and brutally murders his attackers. 

Both are action-packed anime, featuring a strong and badass main character. They both have a lot of violence and gory fights. 

The events in both of these OVAs happen in a post-apocalyptic world. The main characters are both tall, muscular and very powerful men. They also try to help innocent people by killing evildoers in gory and violent ways. 

Both anime have a strong muscular main character that fights against strong enemies. Both are very violent, bloody and over the top. Both are made around the time period (late 80's-early 90's) that have similar character designs as well as similar art and animation. If you enjoyed one, you will enjoy the other.  

Gore & violence, no remorse, killing in one shot. 

Insanely bloody and violent anime's with a badass lead character with super human strength.