Ogata was originally going to be the very first disciple of Ryōzanpaku before Kenichi, however, the elder saw that he had evil intentions. He is revealed to be the true power behind Ragnarok under the name "Kensei-sama"(Almost everybody refers to him as Kensei and not Ogata). He is a Dou Martial Artist. He is fully seen when he goes into the mountains of Yamigata, where he meets Kenichi. He shows Kenichi the path of Asura (which the Elder wanted Kenichi to witness) and it seems he grows an interest in Kenichi, wanting him to become his disciple, though Kenichi turns him down. After learning why Kenichi came to the mountains of Yamigata, he leaves to watch his battle against his disciple Odin. He even tried to stop their fight in order to have both as his disciples, but was dissuaded by the Ryōzanpaku crew. His true skills have yet to be shown, but he can easily kill an Asian bear (described as twice the size of a brown bear.) He can deflect Alexander's sculpture with just his Seikūken. After Ragnarok crumbled, he is revealed to be one of the "One Shadow Nine Fists", the leadership group of Yami. His symbol is flow. He is the latest member to join Yami and acts as the caretaker of YOMI. Tsutomu Tanaka, the Tenchi Mushin Ryuu practitioner in the D of D tournament seems to hold a deep grudge against him.
It is noteworthy that when he first meets Kenichi, he comes off as a kind man seeking atonement; when he fights the bear, he shows his true colors, attacking the bear even after it was already dead.
Kensei appears during a test run of YOMI Rachel Stanley, along with the other masters who had lost their disciples. He recommends the girl to Solcarde, but when asked by Akira Hondo on not taking care of his own disciple issues, he claimed that he still wanted to stick with Odin as he was still a worthy experimental subject. Also, he claimed to have taken up experimenting with disciple training with three other individuals, of which one whose sihoulette greatly resembles Berserker.