Another World: The Demon King Descends

【No System! Otherworld + Rebirth + Magic + Coming of Age + Not an Overpowered Hero】 Mo Fan was a miserable wage slave who was still at work on New Year's Eve. After dying unexpectedly and bargaining his way through the afterlife... He was reborn in another world as the Demon King's son, forced to oppose the hero? What does the future have in store for him? Will he and the hero become sworn enemies who can't live without each other? Will he meet the Demon King's inevitable end? Or will he find the happy, carefree life he dreams of in this other world?