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* First appearance: Battle 48
* Type: Sei / Dou
* Type: Satsujin Ken
* YOMI Symbol: Flow
* Nickname: Odin (Ragnarok and YOMI Nickname)
* Martial Arts: Shintoukei

Ryūto was known as Odin and was the leader and easily the strongest member of the "Eight Fists" and Ragnarok. He is currently a member of YOMI, and has mastered erecting Seikūken (制空圏 lit. Control of the air sphere?), a technique which allows him to create a type of barrier around his defense zone, and can thus neutralize all attacks that enter his defenses. Though he is near-sighted, he makes up for it by possessing the "Inner Eye", an ability giving him a kind of foresight; he paces his opponents and memorizes their attack pattern in order for him to react before the opponent can even attack or defend. He also has a technique called Gungnir, which is a series of rapid and powerful palm strikes which supposedly attacks with 100% accuracy. Besides Hermit, Odin is the only one in Ragnarok to have ever met and trained with Ogata.

His actual name is Ryūto Asamiya (朝宮　龍斗, Asamiya Ryūto?), and was Kenichi's friend when they were little kids, before Kenichi moved out of the neighborhood. They apparently witnessed Miu's martial arts skills when the three of them were only six years old, prompting them to make a vow to become stronger. However, he had always coveted the badge that Kenichi got from Miu, and challenges him to fulfill the "promise" of 10 years ago to fight for its possession. When Kenichi loses to him in a battle, Odin takes Kenichi's Yin Yang badge, and subsequently bends his [Ryūto's] own Yin Yang badge in half, giving it to Kenichi as a loser's present. It also seems that he took a liking for Miu as a child, and claims Kenichi is not good enough for her.

When he fights Kenichi in the final battle, Kenichi appears to have the upperhand against Ryūto until he (demanded by Kenichi) removes his glasses and shows his true strength. Kenichi's skills then prove to be no match against Odin's Seikūken. It is not until Kenichi begins to imitate his masters' style and techniques that he is able to finally overpower him, however, Ryūto becomes enraged and to the surprise of everyone but Ogata, he combines the ki of both Sei and Dou, and once again overpowers Kenichi. However, the powers of both Sei and Dou are not meant to coexist within one body; despite gaining ultimate power, he may destroy his own body, heart, and spirit. In order to save Ryūto from following the destructive path called the "Path of Asura", Kenichi manages to regain his strength. As their fight continues, the strain on Ryūto's body finally reaches its limit, thus he is unable to avoid Kenichi's final attack. As a sign of his defeat, he gives Kenichi back his Yin Yang badge, and is then taken away by Ogata.

During their final fight, it is revealed that during their childhood, when Ryūto wanted the Yin Yang badge that Kenichi received from Miu, Kenichi refused, which is when they decided to fight for it. Apparently, the "unforgivable" thing that Kenichi did back then was give the victory to Ryūto, despite Kenichi being the one who actually won. Ryūto then bought his own Yin Yang badge, but after he got it, he realized that the badge was not what he wanted. In fact, he actually just wanted victory, which is what prompted him to enter the world of fighting; to search for complete victory.

It is revealed in the YOMI arc Ryuto was formally inducted into YOMI upon Ogata's invitation when the latter joined Yami. When he combined Sei and Do the damage left him having his hair turn white, and having a blackened eye, Ryūto is also permanently wheelchair-bound due to the damage the Sei and Dou combination ki has done to his body. However, despite his handicap, he remains a formidable opponent. He is shown to have easily held his own against Shou Kanou's henchmen and Miu Furinji on two separate occasions and does not seem to have any problem in executing his Seikūken and Gungnir despite his condition. However, Miu was still able to throw Ryuto, though he still quickly broke his fall easily with his Seikūken which is an example of current capabilities in his condition. He told Miu about Sho Kanno's orgin is Kuremisago. Kuremisago is a ninja villlage that is so strong one person is an army. He told Miu that Sho spent all his life training martial arts that when he first met her he saw a light in his bird cage. After the D of D tournament he was with Boris, Ethan and Rachel reporting Shou's death to the other members of YOMI. Later after Kenichi's defeat by hand of Tirawit and Kajima Satomi asked him what kind of man is Kenichi. Ryūto calls Kenichi an idiot much to Satomi's amusement.

He is named after Odin, the chief God in Norse mythology. Ryuto bares similar traits towards Odin as he appears to possess the "Inner Eye", and uses an attack called Gungnir that is based on Odin's Spear called Gungnir that always hits his target like Ryuto's attack that has 100% chance of landing an attack.