Dragon Drive

Synopsis

Chibi's body has turned black and he seems even more powerful than before. Reiji fights Lyn and Sue's dragons and appears to be easily winning. However, Reiji is so blinded by rage that it doesn't last long and the twins soon make their comeback.

A dark figure appears behind them and the twins' dragons get even more power. Reiji takes a beating and the twins' escort Sally appears. She tells Reiji explains that the twins are in fact being possessed by an evil dragon named Darx. She begs Reiji to help and Reiji agrees to save them.

Chibi returns to normal and Reiji realizes that rage is not how to unlock Chibi's true potential. Chibi returns to his larger form and they fight the two dragons again. The twins regain control of their bodies long enough to explain that it's too late for them and want Reiji to kill them so they can be free. Then much to Reiji's surprise, the aquatic dragon he'd freed from the twins earlier arrive to help him. With renewed determination. Reiji and Chibi overpower Darx, forcing the evil dragon to flee and freeing the twins.

(Source: Dragon Drive Wiki)