Takeru is a "trainer" born into a family that makes money by training monsters. In order to make money, he accepts requests from the Demon King and works hard to train vicious monsters. One night, a wounded witch visits him and asks him to train a young girl named Anna. In fact, Anna is the last surviving member of the legendary witch clan... Will a bond be formed between Anna, whose ultimate goal is to destroy the world, and Takeru, the best trainer in the demon world? What will become of the world? This is a heartwarming human fantasy work. It won the Excellence Award in the Webtoon Award at "Monocon 2022" hosted by the novel submission site monogatary.com.