Saurva

Saurva is a challenger of Jahy's who sought after her No. 2 seat back in the Dark Realm, she was transported to the human world where she now continues to try and best Jahy.

Saurva is quite ambitious and aims to become the second in rank in the demon world. She thinks she is far superior in power and wisdom in leading the demon realm, compared to Jahy. Because of that, she always looks for a chance to challenge Jahy and beat her, but because of her bad luck or other reasons, she always ends up defeated.

(Source: The Great Jahy Will Not Be Defeated! Wiki)