Late one night, Nana Nanasawa receives a text from her former high school crush, Aya Seto, asking if they can meet. Though they have not spoken since Seto's wedding, Nana enthusiastically agrees, and the two pass time as if nothing has changed since they were younger. Seto's revelation that she is in the middle of a messy divorce leads them to drink the night away. Waking hungover the next day, it does not take long for Nana to suspect that something is amiss. Believing that she has somehow time traveled by 10 years, Nana revisits the place where Seto should be on this day, and to her surprise, her crush stands there exactly as she remembers. Nana does not want to interfere with history, but she is forced to act when Seto is almost hit by a distracted driver. Introducing herself with the pseudonym Mai Sasaki, Nana abruptly resolves to express her feelings for Seto—no matter how assertive she must be. However, she encounters an unexpected romantic rival in her past self. [Written by MAL Rewrite]