Wakamatsu is a prisoner who got released on parole. However, Iwata from the Oowada gang was jealous and started picking on him. After destroying the toy Wakamatsu made for his child, he raged and assaulted Iwata and ended up badly wounded. Due to Iwata's connection to the guards, Wakamatsu's parole got retracted.   ~!As he couldn't bear it, he hanged himself. While transporting his corpse out of prison, handcuffed, Riki Oh broke his cell's wall and came to Wakamatsu's corpse and broke his handcuffs.!~  Wakamatsu was just your average Joe. When he was rushing his pregnant wife to the hospital, he accidentally ran over a person and killed him. If he had luck, he'd only get a sentence to the Ichihara Traffic jail. However, he ran over a cop, so he got sent to a B-class prison (for repeated offenders and serial criminals).

In the late 1990s, society is descending into ecological collapse and totalitarianism. Saiga Rikioh, 21, finds himself in jail. 
Set in the near future, at the privately-owned Tokyo State Prison. Like the chilling wind of the end of a century, a mysterious man with a six-pointed star on his fist entered the pen. 
Saiga Riki-Oh--serving a term of three years, due to assault, his first offense. Riki-Oh openly antagonizes The Four Emperors, four powerful prisoners that control the prison and keep the rest of the inmates in line.

A Retelling of the prison arc of the manga RIKI-OH! 
The story follows Saiga Riki-Oh, a young man blessed with inhuman strength. After taking revenge against a yakuza boss who was responsible for the death of his girlfriend, he ends up in a maximum security prison owned by a private organization. 
The prison is divided into four blocks, each run by a member of prisoners known as the Gang of Four. The first member is a tattooed knife wielder known as Hai that runs his block in a mafia style family system. The second member is a giant man (known as Tarzan in the live action) with incredible strength. The third member is a effeminate fighter named Huang Chaun that is growing Opium in the prison. The final member is a small man that use sewing needles as his weapons.

Husband of voice actress [Junko Sakuma](https://anilist.co/staff/111433).