Ryuji is a former OCUGDF Lieutenant and the younger son of Sakata Reiji, the Chairman for wanzer developer Sakata Industries. Ryuji was born in O.C.U. Japan and was groomed since birth to take over the company. However, he desired the chance to prove his skills in the OCUGDF despite proving to be a worthy leader for the company's future. Ryuji befriended Royd Clive and the two have great respect for one another, forming a brotherly-like bond. In the aftermath of the Larcus Incident, Ryuji found unable to return to Japan and later reunited with Royd when he joined the Canyon Crows.