Debby the Corsifa is Emulous

Debby the Corsifa is Emulous or Debby the Corsifa wa Makezugirai is a fantasy-comedy manga published in Shonen Jump Plus. The plot centers around the 'strongest demon of all time' who, having bested all possible opponents among demonkind, comes to Earth to destroy humans for fun; however, her dim-witted and impulsive nature means that she quickly becomes distracted by earthly pleasures and petty competitions with her newfound human friends.