The story revolves around 27-year-old Arata Kaizaki, who has been unemployed (while also lying about having a job) for several years; only working part-time at a convenience store. One day, a mysterious man named Ryō Yoake offers him a job opportunity. At first, Kaizaki needs to become a tester for ReLife: a science experiment to make him appear 10 years younger to send him back as a high school student. The experiment is supposed to provide a chance to experience youth once again and, in the process, fix whatever is wrong with the subject's life.