I'm Really not a Demon Beast

Li Lin, an ordinary “shut-in”, is transported to another world inhabited entirely by women. There, he unexpectedly awakens the Weapon System—whenever he encounters an enemy, the emotions stirred within him manifest as powerful weapons. As the only man in this world, however, he is rejected by the world’s very will and branded with an Exile Curse Mark. The curse causes his body to gradually shrink until he eventually disappears from existence. To break the curse and survive, Li Lin embarks on a journey into the unknown. Original Webtoon