In 2010, Yoshiyama Kazuko works as a pharmaceutical researcher secretly developing a formula for time travel. When she is left comatose after a car accident, her daughter Akari learns of her mother's first love, Fukamachi Kazuo, from Kazuko's friend Asakura Goro. Believing that finding Kazuo will allow her mother to regain consciousness, Akari uses Kazuko's formula to leap back in time to the 1970s in hopes of finding a younger Kazuo. Instead,
