My Left Hand Can Mutate

Humans have undergone genetic mutations, resulting in some individuals developing extraordinary abilities while others turn into monstrous creatures. The male protagonist, once transformed into a monster, rediscovers his humanity through the female lead's sacrifice, granting him a second chance at life. Now reformed from his playboy past, he commits to protecting the female lead, hiding his true nature among superhumans. Secretly, he uses his monstrous form to hunt other monsters and taps into the power of an ancient demonic deity, with the goal of preventing its resurrection.