Cold-Blooded Umewakamaru!.Gyuki's past is revealed. As a human he was once known as Umewakamaru, a noble child who excelled at everything. After his father died, his mother left him at a monastery. News of his mother's illness prompted Umewakamaru to want to see her. On the way he was tricked by demons into going the wrong way. There he found that his mother had been devoured by the yōkai, Gyuki. Umewakamaru went mad with grief and killed Gyuki and in his altered mental state he started killing other travelers. In time he also came to be known as Gyuki. It is then that Rikuo's grandfather, Nurarihyon, met him for the first time and after defeating Gyuki in battle requested that he join them as a member of their family.