To see a happy ending, I race through time.

In the summer of his second year of high school, Yushin, who had lost his beloved grandfather, meets him at a place filled with memories of his grandfather while carrying his grief. That was the beginning of everything. By chance, Yushin travels back in time twenty years, and with the cooperation of his grandfather in his youth, he rushes about to prevent his grandfather's love with his girlfriend from ending in tragedy. And Yushin had one more reason to rush about.