Young Brother-in-law Is Now My Husband - Chapter 16: The Perverted Old Man!!

mc gets transmigrated to Fallout New Vegas with the merchant system. let the questionable adventure begin.

He is a young man without a spirit root. It is believed that this denies him the chance at cultivation. However, a mysterious lady imparts a Supreme Demon Classic to him and from then on, he starts his path of cultivation.
He undergoes a total transformation to emerge as the most fearsome and powerful fiendish demon in his era, that even immortals and fiends are fearful of him, and saints are at his beck and call.
Mastering the Supreme Demon Classic is the turning point in his life. He is able to unleash his immense and divine power from within, illuminating the entire universe!

“You died.”That was what the mysterious figure told him, but then he was given a second chance for the good deeds that he did in his previous life.“Super Prodigal System!”“Cultivate to immortality by wasting as much money as you can!”For the former number one prodigal of Earth, this was the perfect system!

What could be worse than getting married to a demon prince as a human princess for a forced truce?Being in a place surrounded by demons was like a nightmare to Aelin. Demons and humans have always despised each other after all. But things only go downhill, when her husband leaves her shortly after they spend a night together to go fight a war with unknown beings which leaves Aelin at the mercy of her enemies