Rengokuki

is the original demon who was chosen by Entei as his rider. Resurrected by the return of Entei, he attempts to continue terrorizing villages to conquer the world. He attempted to make Kagura his mate, but she had no interest in him whatsoever, saying that she didn't think he looked like he could take over the world. After Kagura rejected him, Rengokuki chased after her on Entei in anger and attempted to kill her. But before they were able to battle one another, Hakudōshi appears and says he'll take on Rengokuki. Rengokuki scoffs at the child, thinking he is no match for him at first glance. Entei then throws Rengokuki off of his back, and stares at Hakudōshi, transfixed. This action shocks Rengokuki, who then vows to destroy the boy to prove to Entei that he is its' true owner. Rengokuki swung his naginata at Hakudōshi, but missed him completely; Hakudōshi stood on the end of the weapon, much to Rengokuki's astonishment. Hakudōshi then easily took the naginata out of Rengokuki and brutally killed him with it, his own weapon. After Hakudōshi killed Rengokuki, Entei chose Hakudōshi as his new master.