Ryuji is/was the boyfriend of the most popular girl in school, Tomoko. However he was also playing around with many other girls, too. This of course upset poor Tomoko who then went on to flirt and then chase after Junta. Enraged, Ryuji sent a few punks to beat Junta up. In the melee, both Tomoko and Ami were hurt. After seeing Ami get hit by one of the punks, Junta immediately changed into the Megaplayboy and went on to easily defeat them. Still angry, Ryuji confronted Tomoko about her new love to which Tomoko ran off into Junta's arms. Ryuji immediately went after Junta only to be accidentally shot by another of Karin's DCM bullets. Karin had apparently received a new bullet that would eliminate the Megaplayboy DNA permanently. Unfortunately, instead of shooting Junta, Ryuji becomes the victim. Recovering from the accident, Ryjui realizes he now has the power to change his form to whomever he wants. Using his new ability, Ryuji pretends to be Junta and hurts both Tomoko's and Ami's feelings. Eventually he is confronted by Karin and they both battle. In the end, Karin was defeated after Ryuji copied her DNA and used her own tactics against her. Now apparently insane from aborbing too many people's DNA, Junta and Ami then come onto the scene and face off against the now powerful and insane Ryuji. After being beaten several times, Junta finally decides to change into the Megaplayboy despite Karin's warning that he'd never be able to change back after this. Finally, as the Megaplayboy, Junta defeats Ryuji who then ends up in the hospital. Strangely, Junta was able to revert back to normal. Most likely due to Ami's effect on him. Having seen all this, Tomoko stays by Ryuji's side as he heals and she returns to being his girlfriend.