Helck.

Three months have passed since the Demon Lord was struck down, and the Demon Realm is holding a tournament to select his replacement. The leading contestant is Helck, a human hero who claims to hate his own kind. Some aren't happy with the idea of a human becoming the next Demon Lord—especially Vermilio the Red. She wants nothing more than to protect demonkind and prove Helck to be their enemy, even if she has to rig the competition to do it!