約束のステージ ～時を駆けるふたりの歌～

20-year-old Ozawa Tsubasa has been helping out in the eatery that her mother Yukiko runs in a port town in the Tohoku region. She loves songs and secretly wishes to become a singer. However, she is on the verge of giving up that dream since it is practically impossible. Seeing her mother keep on working despite the hardships as well as the deserted town, she doubts that dreams and wishes come true. But one day, Tsubasa travels back in time to Tokyo in the year 1975 in an unexpected way. She meets 20-year-old Ozora Tsubasa, a cheerful and positive girl with the same name and dream as her. The unsuspecting Tsubasa had left home and come to Tokyo under the mistaken impression that she was scouted by a television station.