Based on the same-titled manga series by Yayoiso, this movie follows Arata Kaizaki, an unemployed 27-year-old man with limited money and no girlfriend, who is approached by Ryo Yoake, a researcher at the ReLIFE Laboratory, for an experiment. He is given a chance to rejuvenate his appearance by a decade for a period of one year but the catch is he has to attend high school for a year. There, he gradually forges friendship with a group of classmates, falls in love with a girl named Chizuru Hishiro, while keeping in mind that after the one-year period is up, he will be erased from their memory.