Chainsaw Man

Chainsaw Man is a Japanese manga series written and illustrated by Tatsuki Fujimoto. 

Chainsaw Man follows the story of Denji, an impoverished teenager who makes a contract that fuses his body with that of Pochita, a dog-like Chainsaw Devil, granting him the ability to transform parts of his body into chainsaws. Denji eventually joins the Public Safety Devil Hunters, a government agency focused on combating Devils whenever they become a threat to Japan. The second arc of the story focuses on Asa Mitaka, a high school student who enters into a contract with Yoru, the War Devil, who forces her to hunt down Chainsaw Man and seek revenge against him for her near-destruction.