psycho but it's okay

Lee know was abused by his mother when he was a young child. He only had his cats as his companion. But, when his mom tried to hurt his kittens, he ran away from the house and started living alone. As time went by he got lonely and depressed and eventually he started killing depressed people like him, with a belief that he is giving freedom for his victims from this cruel world. But, he starts changing when y/n enters his life. Find out what happens and how she manage to change him into a normal person