A 27-year-old washout gets turned into a high school kid for one year, and instead of using it to fix his life, he just becomes a better person by accident. The show knows the premise is borrowed, so it doesn't pretend, it builds everything around watching someone who has already failed learn that failure isn't permanent, just something you carry into the next room. By the final episodes you realize the real experiment wasn't about the drug at all, it was about whether someone could forgive themselves, and that's when it stops being a gimmick and becomes something you feel in your chest.

Kaizaki Arata is stuck. At twenty-seven, he's unemployed, rejected by every company that interviews him after he quit his first job, and written off as a loser by the people around him. Then Yoake Ryou of the ReLife Research Institute offers him a way to turn things around: a mysterious pill that makes him look seventeen again, as the subject of a one-year experiment. Kaizaki takes it without much thought and must spend that year as a high school transfer student. He expects his extra years of experience to make it easy, but his first day proves him wrong. He fails every test, is badly out of shape, and is lost among school rules that have changed over the past decade. Ryou is assigned to watch over him, much to his irritation. The comedy drama follows Kaizaki as he adjusts to this hectic new routine, tries not to repeat his old mistakes, and gradually learns more about his classmates.