Denji

Denji as a young boy, inherits his father's debts from the Yakuza. After meeting Pochita, he becomes a Devil Hunter for the Yakuza in attempt to clear his debt. After being betrayed by the Yakuza, which were under the control of a Devil he died and Pochita became his heart. He now has the ability to become a Chainsaw Devil by pulling the cord on his chest. After meeting Makima, he became a Public Safety Devil Hunter.

(Source: Chainsaw Man Wiki)