The main character of the show, Riku was originally borne in the Heian Era of Japan as Youmei. His mother sent him into the future, where he was taken up by Soutaru Tachibana, to avoid dying in the Chi-Ryuu raid on the Ten-Ryuu shirne. At the start of the series, he's shy, and easily scared. But when he receives the Ten-Ryuu Toujin drive containing Kogenta, Kogenta helps him to become a lot braver and stronger. He has no memory of his time in the Heian era until he goes to Naraku to reunite with Kogenta after losing him by Yuuma and Rangetsu. In Naraku, he sees his memory play in front of him, and learns of his past life. He is the head of the Ten-Ryuu.