On her first day of high school, Ichihara Yui is helped by someone she assumes is a teacher, but when she gets to class she finds out he is in the seat next to her. Itsuka Daisuke was born at the end of the Showa era and he has returned to experience the high school life he never had, even though he is ten years older than all the other students. Yui takes up the task of helping him fit in so they can enjoy the springtime of their youth together. Included one-shot: Irotoridori no Sekai