When he worked with Kurama, Yomi had only two ears, but after he lost his sight, he gained four more as his body was forced to adapt to a sightless existence. He has long, black hair and two prominent horns that jut down from his forehead but appear to frame his head. Additionally, he has four horns on his head, two on each side, and one jutting from the back of his head, giving him a total of seven horns. He also wears a light garment underneath red robes and has a defined musculature. Kurama caused Yomi to become blind by planning an attack from a rogue demon on him.
Personality
When he was younger, Yomi was brash and reckless. He often got himself into trouble and needed to be rescued by Yoko Kurama. His recklessness and other factors contributed to his being blinded, literally, by his ambition. However, on the verge of defeat, he always turned to a more timid character, despite never begging for mercy in battle. After losing his sight, Yomi is a calm person, who thinks before he acts even in battle, which is arguably what contributed most to his growing strength.
He also genuinely loves his son, Shura, who he fought in the Demon World Tournament. Rather than fight at full strength, like Shura wanted, Yomi was actually helping his son become a better fighter. He also gets along well with his subordinates, but can also be quite the manipulator, Yomi being the first person to outwit Kurama and get away with it. Yomi seems rather cold-hearted but while it seems like he would kill his son, he's just establishing a will to fight in his son. Yomi also seems determined to ensure Shura does not grow up as he did, bloodthirsty and impulsive. While Yomi does not display any particular hatred for the human species, he does seem to believe demons may consume as many of them as they please, claiming humans are plentiful in number and "reproduce as if they are fighting extinction as it is".
His encounters with Yusuke Urameshi has Yomi uncovering parts of his personality that he had never discovered before; namely, that of his primal demon self and the allure of a decent battle in the hopes of winning it all.
It is notable that despite being on relatively good terms with his enemies now (i.e. Yusuke), he still has not given up on the goals of unification he possesses in the Demon World, and will continue his plans if he ever wins the tournament.
Synopsis
Three Kings Saga
After Yusuke is granted admittance into Makai to see his dying ancestor, Raizen, Kurama is given a "spirit of words" (video message) from Yomi. Kurama decides to join Yomi, despite the fact that Hiei is working for Mukuro and Yusuke for Raizen. On Kurama's first day, Yomi brings him to the demon that took his sight and notices Kurama's change in heartbeat. He explains their past as partners, and tells Kurama that he (Yomi) was a child, and Kurama was right for sending the demon after him.
Yusuke then orchestrates the Demon World Tournament, and asks Yomi to join. Reluctant at first, Yomi agrees after 7 of his top subordinates (Kurama, Jin, Chu, Toya, Rinku, Shishiwakamaru, and Suzuki) betray him and side with Yusuke as well as realizing Mukuro had complied. When he felt the power of Raizen's old friends, Yomi truly dissolved his country and decided to enter the tournament to test himself. Before the tournament started, he informed Yusuke about his change, but didn't care if Yusuke believed him or not. During the preliminaries, Yomi was matched against his son, Shura. Despite the younger demon throwing every attack he had, Yomi proved that he was easily more powerful, eventually convincing his son to concede. He fights Yusuke in the second round. At first, his impenetrable shield is more than a match for Yusuke's Demon Gun, that is, until Yusuke mixes his spirit and demon energies into his attack. In the end, both are injured, and only the cry of Shura convinces Yomi to stay on his feet as both begin to fall. However, drained of energy, he loses the next match to Kokou, one of Raizen's old friends. Later, when he planned to leave on a journey with Shura, he reconciled with Kurama and told him to tell Yusuke that he would like to fight him again, although he wasn't sure of another victory. As he left, he told Kurama that he was glad he accepted his invitation.
Techniques/Moves
Since he lost his sight, Yomi grew four extra ears to compensate for his lack of vision. Yomi's sense of hearing is so great that he claims to be able to hear every word being spoken in his kingdom of Gandara. He is also able to accurately pick up on changes in an organism's heart rate, allowing him to guess facial expressions and current emotional composition, despite his lack of sight. Having modeled himself after Kurama, Yomi is a calm, calculating fighter, being able to measure the exact speeds of the opponent's attacks with his hearing, and activating his barrier at the moment of impact so as to not waste energy. In the manga, Yusuke says that someone told him that Yomi's ability to fight purely by sensing ki and relying on hearing takes a massive amount of concentration and stamina, Which is one of the main reasons that his fight with Yusuke went on for so long despite his power advantage over Yusuke.
Demon Energy Absorption Wall (魔古忌流･煉破反衝壁, Ma Koi Ryū･Renpa Han Shō Heki, literally translated as Ancient Envious Demon Style･Distilling Destruction Opposing Force Wall): is a green spherical barrier that protects Yomi from demon energy-based attacks. Only by using a combination of Demon Energy and Spirit Energy was Yusuke able to pierce it. Spirit energy completely bypasses the technique, however.the barrier acts as filter to absorb demon energy.its been seen spirt energy doesnt inflict harm on yomi seeing how spirit energy can go through the barrier but isnt strong enough to kill yomi.
Superior S Class Energy: Yomi is a experienced Upper S class Mazoku, he is extremely powerful. Its been shown that he can completely outclass other extremely powerful Upper S class demons like Yusuke due to him being a very powerful calculating fighter and being very experienced at combat because of his age.
Energy Blasts: Yomi gathers green demon energy in his hands and sends it towards his opponent. He demonstrates the ability to manipulate the size of these energy blasts during his fight with Yusuke.
Energy Blast Barrage: Instead of firing a single blast, Yomi fires multiple blasts from a single orb of energy at his opponent. This attack is similar to Yusuke's Shotgun.
Energized Punches: Yomi charges his fists with his demonic energy, increasing his physical punching power. This ability is also reminiscent to Yusuke's ability to concentrate spiritual energy into his fists.
Relationships
Yoko: Yomi in the past was a subordinate of Yoko's, pillaging and plundering villiages and domains under his leadership. They were partners in crime, bandits, but not close friends. Yomi was fool-hardy, headstrong, and eager to jump in to battle at the nearest opportunity. He acted on a whim, costing Yoko the lives of many cohorts and eventually forcing him to act for the good of his bandit outfit. He betrayed Yomi, ordering his assassination; however the attempt failed but left him blinded, forsaken by the light.
Kurama: Yomi undoubtedly senses his old acquaintance Yoko's identity struggle, and initially intents to force Kurama's old self to the surface for his benefit, and to reforge the bond they had in the past. He states that he admires Kurama for all that he's done, and that he learned a lot from him. In some ways, Kurama served as Yomi's idol, and as the Three Kings saga progresses, we see that Kurama's opinion is greatly valued by Yomi. The two form something of a loose alliance, loose because Yomi makes sure he "protects" his investment in Kurama's counsel through blackmail. Kurama even betrays him when Yusuke proposes the Demon World Tournment by going back to being an individul demon and threatening to side with Yusuke (along with 6 others of Yusuke's friends) if Yomi didn't agree to it. During the Makai Tournament, Yomi seems to accept Kurama's decision to suppress his Yoko identity, as he has come to experience a similar bond with his son. Yomi offers assistance to Kurama after his battle with Shigure and the two part ways as friends at the end of the tournament, something that shouldn't have been possible given their past history.
Shura: Yomi's clone of himself is in every way a son to him. He inherited Yomi's strong will and ambitious tendencies, along with his vices. Yomi takes it upon himself to impress onto Shura, the importance of knowing your enemy and yourself, and to not make foolish gambles with his life. He genuinely cares for Shura, whose birth formed what is undoubtedly the closest bond in Yomi's life. Shura even influenced Yomi's decision to compete in the Makai Tournament as an individual, which required his surrendering all his power.
Yusuke Urameshi:: As the descendant of Raizen, Yusuke and Yomi were automatically enemies from the beginning. When Raizen died and Yomi and Mukuro were on the brink of war, Yusuke went to Yomi to introduce himself as the new king of Raizen's country. During the talk, Yusuke proposed the dissolution of the separate countries in favor of the Demon World Tournament to unite th Demon World under one ruler. At first, Yomi hated the idea, but had to go along with it when Kurama and 6 other subordinates who were all friends of Yusuke sided with Yusuke and Mukuro agreed to his terms. However, after feeling the power of Raizen's friends, Yomi grew excited about the tournament and came to respect Yusuke, seeing him as a friendly rival and not an enemy as Yomi initially saw him. He was happy to fight with Yusuke and felt it was a good chance that Yusuke would surpass him by the time of the next tournament.
Trivia
His name literally translates to "Underworld."
In Chapter 161 of the manga, he is stated to have a Youki of 1,550,000.
Yomi deliberately lowers his energy level (but not his spirit class- he remains upper S class), in order to enjoy his fight with Yusuke. As a consequence, he takes too much damage, and loses in the very next round to Kokou. This occurs in the third round.
Quotes
"Your betrayals have taught me much. And today I feel better— For all the pain of the past." -Episode 108
"It's amazing isn't, how people change?" -Episode 108
