This demon boy was too much of a brat.
He was the son of Yomi artificially grown to help his father win against Mukuro. They both enter the Demon World tournament together.
He sadly has to fight his own dad eventually early on.
Where he is taught a painful lesson in humility.
So after his loss, he cheers his dad on in the crowd.
After they both lose during the tournament, they both go on a journey to get stronger but more importantly wiser.
His dad definitely had a handful.