High school senior Takashi falls in love with a girl named Azusa at first sight and the two begin dating. One day, Azusa makes a strange confession, telling Takashi that everyone forgets her a few hours after meeting her. At first Takashi doesn’t believe Azusa, but over time he begins to realize that he’s starting to forget the details of their time spent together. Soon he begins leaving notes documenting their time together so he doesn’t forget.