Kou created songs and uploads them to the Internet, and Yuka and Saki enjoy his music as fans, always listening with deep interest and admiration. Their final summer vacation has begun as junior high school students.

Miyuki works as an OL. Her younger sibling died from a car accident in 1989. Due to her sibling's death, her mother became ill and her father drank constantly until he died. Miyuki believes if she could prevent the car accident, her family would have a happy future. She travels back in time to 1989 and struggles to save her younger sibling from the car accident.