The End of the World: I Am Possessed by a Monster

The Male Protagonist Can Transform into a Monster and Can Change Back at Any Time

The female protagonist is dispensable, the male protagonist is not a virgin

Have You Ever Become a Parasite Controller?

The Protagonist Merges with a Strange Creature, and Then Some Strange Changes Occur

The Protagonist Has Two Identities, One Is Human, the Other Is Demon or Weird

Novels in Which the Protagonist Becomes Less and Less Human or a Normal Creature

Want to watch something like "Guest, your mother's tentacles are crying!" Book. Like "Guest, your mother's tentacles are crying!" ] The image of Dr. Apple (either on the battlefield or in person), the weirder the better.

About Possession and Body Seizing Control Types

Is there anything about possession, body seizing, and control types?

Possession, Seizing One's Body

The Male Protagonist Was Parasitized, Controlled and Changed, and Became No Longer Human.

Parasitism can be used to replace disguise (preferably the whole human kind, similar to the Lost City of Beasts)

The Protagonist Is a Weird Creature, or Can Become Weird

Just Now, I Wanted to Attach a Tattoo

Can be possessed by various monsters, objects, ghosts and the like. Or the card can be transformed

The Male Protagonist Is Possessed, Something Like Venom

The male protagonist is possessed, something like venom