Xenosaga II: old email

Playing through Xenosaga II's postgame, enjoying the bosses on display so far. Trying to figure out what's up with the email "UU-KUN@xenosaga.com", which a robot named CAMPARI mentions after you beat >!Dark Erde Kaiser!<. It says that if you send the three names of three superbosses to that email he would give something to help out. Does anyone know what the reward would have been? Google Search doesn't seem to have anything about it.