At the age of 27, the life of Kaizaki Arata (voiced by Kensho Ono) has reached a dead end. He quit his job after only three months of work. He failed twice in the postgraduate entrance examination. He wanted to find a job to make a living but failed repeatedly. Arata didn't know and didn't want to know what was waiting for him in the future. One day, Arata was walking on the street in a daze and accidentally met a mysterious man named Ye Mingliao (voiced by Ryohei Kimura), who invited him to participate in an experiment that looked extremely ominous. In the face of the huge temptation of benefits and the promise of being able to find a job, Arata, who was full of doubts, was shaken. According to the requirements, Arata will take a mysterious pill, after which his appearance will return to the appearance of 17 years old. Arata needs to enter the third year of high school. The whole experiment will last for one year. In this way, Arata returned to the campus. What kind of life will be waiting for him here?