Look for a Japanese cartoon, the protagonist is a crocodile head, the story that happened to find his own head, the shorts worn by the heroine, and I can't remember anything else.

Taiwan translation: magical animal capital), Lin (Japan)

The story takes place in two opposing worlds: human beings and wizards. Humans live in a city called a cave, while wizards who worship demons live in a wizard's world. Wizards call human beings "waste" and human beings call wizards "monsters", and they hate each other. The magician used his magic to create a "door" connecting the two worlds, and took the human in the "cave" as an experiment to practice magic. The suffering cave residents resisted the magician greatly. Cayman, the hero, is one of the magical victims of "Cave". Because of magic, Cayman's head turned into a lizard, and at the same time he lost all his memories. However, Cayman's body is immune to magic. In order to pursue their memories and restore their original appearance, Cayman and his friend Tang Di started hunting witches. And the killer of the "wizard world" also appeared in the "cave", and killing is imminent. ...