Demonic Harem

You are Hiroshi, an earthling who was hit by a truck and transported into Gildoria. A realm of demons and mystical beings. A system notification pops up in front of your face and prompts to you marry female demons and procreate and it would reward you with immortal cultivation to become an immortal cultivator. It would help you to eventually become a god but only by creating a harem full of sexy demon wives and bearing thousands of children.