Reincarnated! My Parents and Brothers Beg for My Forgiveness - Chapter 21

Xue Xi is forced to fall in love at first sight with this dangerous man on their first meeting. With death being the only other option, she makes the first move:

The Supernatural era descended, the rules changed, mystery arrived, and the world altered. Countless ruins of civilization emerged, and an abundance of Heavenly Materials and Earthly Treasures lay at everyone’s fingertips. Radical faction, “This is the best of times, entering a new world, excavating relics, mass evolution!” Conservative, “This is the worst of times, with countless monsters outside, once you leave the Safe Zone, extinction awaits humanity!” … Meanwhile, at a remote ruin, Lu Yuan successfully discovered new treasures and sought after the mysterious wealth, desperately trying to contact his fellow Earthlings. “Found a communicator, can it get through?” “Hey, humans—I’m almost becoming a god, and you’re still hiding in the Safe Zone?”

Three Days of Happiness is a novel by Sugaru Miaki, also known as Fafoo. It’s a rewritten version of the story originally posted to 2ch.

The premise of the story revolves around a shop where one can sell away the remaining years of their life, and the consequences of doing so.

“I Say A Little Prayer” is a short related story which was posted along with the novel’s release. It spoils some things about the main story, but nothing major.