A manga about a demon lord who wants to be defeated by the hero quickly is a Manga/Manhwa/Manhua in (English/Raw) language, MONSTERS series, english chapters have been translated and you can read them here. You are reading A manga about a demon lord who wants to be defeated by the hero quickly chapters on ManhwaZ, fastest updating comic site. The Summary is
The demon lord who has come to the mortal realm, accompanied by her followers has a secret that no one can know — She has to be defeated by the hero. Will she be able to lose to the hero safely?