Yomi is a prisoner of Kokubu Prison and a member of the Four Emperors. He is the boss of the west block.
Yomi, and the other Emperors (Kitamakura and Shiragami), are first introduced after Riki- Oh killed Narumi, one of the Four Emperors and leader of the north cell block. Yomi is an effeminate, but also ruthless and sadistic man, even as going far as killing a young boy named Asa by skinning him alive for revealing a greenhouse containing opium to Riki-Oh, and beheading a dog. He is also able to kill people by striking them in the chest with his palm, slowly stopping the victim's heart. After the Warden digs up Riki-Oh when he was buried alive for seven days, Yomi and Shiragami proceed to viciously torture Riki-Oh by smacking him around with a monkey wrench and stuffing a handful of razor blades into his mouth. After that scene, Yomi and Shiragami are not seen again. However, in the first OVA, Riki-Oh later battles Yomi and Yomi dies when the greenhouse is destroyed, burying him alive. In The Story of Ricky, Riki-Oh battles Yomi in the prison kitchen and Yomi is defeated by Riki-Oh after he severs Yomi's leg and breaks his arms to make sure that he could never kill again.
Yomi is a young effeminate boy. He has short black hair with a tuft hanging over his left eye.
Yomi is arrogant, sadistic, and vengeful man. He is faithful to Kokubu Prison and he doesn't show mercy to traitors.
Yomi is the most powerful of the Four Emperors and one of the most powerful
characters in the manga. He and Shiragami are the only to have repeatedly defeated Riki. He is able to stop the opponent's heart with a blow to their chest. Yomi is also one of the fastest and agile characters. He can kill an opponent by skinning them with a very fast scratch. He shows to be able to squeeze his own skeleton in order to evade from ropes that keep it tied, then return normal.
- Yomi is the only character who has injured Riki and has not been punished for it.
- Given its power, the secret planting of opium was put in the West block that he ruled.
- He and Shiragami disappear before or during the rebellion of the prisoners and do not reappear. Their current status is unknown.
- Yomi or Yomi-no-kuni (黄泉 or 黄泉の国 Yellow springs/wells) is the Japanese word for the land of the dead (World of Darkness). It´s the shintoism version of Hades, where the souls of the dead are tortured forever.