Fangs, Claws, Scales, Heterochromia, Horns, Tentacles 😫

Ideally, the protagonist gradually changes and grows these structures while living in human society. The next best thing is for the protagonist to have this kind of body structure from the start. //////// Transmigrating straight into another world as a demon or demon king works too. //////// Give me protagonists who make you lose sanity!