After a string of job failures, 27-year-old Arata Kaizaki encounters Ryou Yoake from the ReLife Research Institute, offering him a chance to transform his life using a mysterious pill. Upon taking it, Arata wakes up as a 17-year-old and is tasked with reliving high school for a year as part of an intriguing experiment. Despite his confidence in handling the situation, Arata faces academic struggles, physical challenges, and clashes with updated school norms. As Ryou shadows his every move, Arata must navigate this second chance, learning from his blunders and unraveling the secrets of his classmates in the process.