Yōma of Mephistopheles

Essentially, Yoma is an adult version of Tenma of Pegasus. He shares a physical resemblance to the Pegasus Saint, only older, and has a bit of a beard. Unlike other Specters, Yoma usually wears a wrinkled tuxedo and his top hat, which is one of his most recognizable features. When he manifests as Kairos, his pupils turn black.

Yoma is an atypical character, always shrouded in mystery. He commonly refers to life as a play, speaking as if he were acting and making references to Shakespeare. He is quite a joker, very talkative and disorganized. He always seeks to create the "spectacle" he wants for his amusement.

During the 18th century, Yōma lived in Japan, but during a war against the Shogun, he escaped on a ship, following the impulses of the evil star that was beginning to awaken within him. During his voyage, he saw the soul of Pegasus flying like a comet in the sky, which he followed, leading him to Heinstein Castle in Germany, along with the other specters who had awakened. He lived in the castle for a long time, where he fell in love with and married Partita, a servant of Pandora, with whom he had Tenma. Shortly after, the soul of the god Hades was born from Pandora's mother, after which Yōma stole Hades' soul and left the castle, all to prepare his future plans. At that time, he began to live a human life, posing as a priest to find the child destined to be Hades' host, and thus he managed to find Alone and place the soul of Hades in his corresponding body of that era at an early age. He appears in the Sanctuary looking for the Saint of Pegasus, but not finding him, he encounters the young Aspros in training, where he makes him believe that his brother was preparing to surpass him, thus leaving a drop of darkness in Aspros' heart. Years later, he decides to confront Aspros in battle, so he decides to lock him in the Wonderful Room, and then go to confront Tenma, Shion, and Regulus. Yōma begins to show Tenma the past, showing him as a newborn in the arms of his mother, Partita, surrounded by a young Pandora, and Yōma himself, his father, something that Tenma refutes, as he believes his father died years ago. He reveals that he did not really die, upon becoming a specter, but that he saw Hades born from Pandora's mother on a snowy day, so he decides to escape from the place, to avoid becoming a victim of Hypnos and Thanatos, disguising himself as a monk.

He begins to torture Tenma and Athena, making them doubt their true role in the Holy War, so he decides to leave them alone and return to Hades. It is finally revealed that Partita is not dead, and he transfers Partita and Tenma to the Temple of Saturn. After the battle, he is seen observing from another Temple, waiting for his opportunity to act. After finding Tenma and Shion, Youma begins to activate his powers to reveal the future to them, showing them Seiya of Pegasus in a coma due to Hades' sword. He also reveals that his goal is not to serve Hades, but to kill Seiya and change the future, thus causing discord in Olympus itself. After the revelation, they return to the underworld and this time he decides to send Shion to the Fourth Wonder. But to his surprise, the portal opens again, but this time someone emerges from it: Aspros, carrying the unconscious Dohko and Shion in his arms. After a conversation, he tells Tenma to leave him alone, that he will take care of the specter, so the battle finally begins. During the battle, Aspros takes advantage of the fact that the place where they are is not affected by Youma's time control ability. But Youma begins to tear his clothes, finally revealing the Mephistopheles armor. After this, he uses his biological reset, which causes Aspros to revert 200 years in his biological clock. Believing him dead, he decides to confront Hades on his own, but Aspros reappears, this time wearing the Sapuris, which is why he is unaffected by Mephistopheles' attack. Once this is done, Aspros uses his Final Destination on Youma, killing him instantly. But this only reveals Youma's true body, revealing himself as the reincarnation of Kairos, the younger brother of Chronos, and he wants revenge on him for sealing him away. Aspros tries to attack him, but even his Galaxy Explosion is useless.

After this, he uses his Great Wonderful Fourth on Aspros, intending to crush and pierce him with the arrows of his armor, but Aspros is protected by the Gemini Golden Saint armor, guided by Deuteros. After revealing that he is not a true god, but that his body is enclosed in a human, he makes him see his mistake that he can be wounded, age, and even die. After this, he uses the Rosary of 108 Beads to imprison the specter, placing the rosary between his arms and using his Galaxy Explosion, which definitively ends the demon's life. After Aspros disintegrates in front of Athena, Partita appears in front of Tenma holding a sphere from the 108 Beads. Looking closely, Tenma observes that it contains the lifeless body of Youma, which has a clock making its characteristic sound. Then Partita appears holding Youma's dead body, shattered and bleeding, but a smile can be seen on her face, revealing to Tenma that only in front of her mother was she truly happy, something he doesn't believe. Finally, it is revealed that the one holding the rosary was none other than Alone himself. Years after the end of the Holy War, Youma manages to escape from the rosary of 108 beads and attacks the Sanctuary in search of Shion, as it is the last time he can change the future to his liking. After fighting Teneo and almost eliminating him, he is teleported to where the statue of Athena should be. When he is about to kill Shion, the spirits of Sasha and Tenma return from death and defeat him using Athena's shield.

•Marvelous Room: Yōma summons a vortex of rotating black waves that allows him to create an area where neither time nor matter exists. Anyone who receives this technique is immobilized and their body is disintegrated at a quantum level. According to Yōma, even the souls of his opponents are reduced to nothingness. • Rewind Bio: Manipulate the time of a biological organism backward as much as you want, allowing you to return an enemy to a prenatal stage. •Real Marbleous: Yoma generates a series of dark energy vortices that trap the opponent in a whirlwind and pulverize them while their body spins inside. Yoma constantly releases a large amount of dark energy while spinning, capable of crushing anything it touches. •Rewind World: Manipulates the time of a biological organism backward as much as it wants in a large area, thus it can return an opponent to an embryonic stage, even to never having been born.