The masked man, Ritsu, is the fourth Hau Dragon robot pilot sent to destroy Zeorymer. He wears a mask, because he was born with the face of a woman. Because of this, he is berated by his team mates, forcing him to wear the mask.
Ritsu's robot, "Rose C'est La Vie of the Moon", is arguably the second most powerful of the eight robots created by Masaki Kihara, the first being Zeorymer. It is heavily armed, storing multiple beam cannons, lasers which could be focused into blades on the tips of the robot's fingers and finally the J-Kaiser, a massive energy cannon.
Ritsu is also the only pilot to fight against Zeorymer when Miku Himuro is not present within the robot. This greatly reduces Zeorymer's chances against the behemoth.
However, despite all these advantages, Miku eventually combines with Zeorymer, activating the Dimensional Coupler System. Zeorymer unleashes it's Meioh attack, destroying Rose C'est La Vie with Ritsu.