Selling a Kidney at the Beginning: Immortal, I Pretend to Be Strong

[Immortality + pretending to be strong + micro harem without pornography] Gao Quan, who has immortality, sells his kidneys at the beginning, and when he awakens and pretends to be strong, the system becomes stronger. The system takes him along, and the protagonist fights monsters all the way, upgrades, and finds a wife. It's so exciting that he flies away!