Chainsaw Man the Movie: Reze Arc

Denji's life took a drastic turn after his father's debt led to poverty and isolation, with only his pet devil, Pochita, by his side. To make ends meet, Denji hunted devils with Pochita, but the yakuza ultimately exploited their efforts. Denji's dream of a simple life, complete with a loving girlfriend and good food, was cut short when he was betrayed and killed by the yakuza. Pochita's old contract allowed him to merge with Denji's remains, granting the deceased boy devil powers that transformed his body into a chainsaw-wielding hybrid.