Yi Ba Shazhudao, Kan Fan Wan Jie Hen He Li Ba?

Ye Chuan—a mental patient—sees all living creatures in the world as pigs. On the day he changes professions, he awakens a life-class occupation: Butcher. His teachers and classmates are gravely disappointed, and even his childhood sweetheart leaves him. However, the Butcher profession grants him extra damage against pigs and halves the damage he receives from them. Since he sees everyone as pigs, he uses a single butcher’s knife to rise up and become a god!

(Source: Kuaikan, translated)