Roger Quinn time-travels into the body of an ancient refugee. Right after arriving, his sister saves his life by cutting her wrist to feed him her blood. He then discovers that his ruthless grandmother and relatives are about to sell her to bandits in exchange for food. At this critical moment, he enables the Group Buy Recycling System. With its help, he uses food to rescue his sister, humiliates his wicked relatives, unites the refugees, meets the current dynasty's princess, helps resolve the empire's crisis, and wins the beauty's affection.
