Like so many of the young Zoid hero's, Ruuji happened to fall into his Murasame Liger when his peaceful village came under attack by Bio Zoids in episode 1. The liger seemed to come alive for the boy and from then on it was Ruuji's Zoid. It just doesn't respond to anyone else.
Ruuji is young and inexperienced as a Zoid pilot, but his adaptability and determination are to be applauded.
He has strong moral and family values and doesn't like to see undo death and destruction. He will go out of his way to protect others even if it means risking his own life. He seems timid and screams a lot, but I'm sure we're going to see him mature as the episodes progress.