Forget Me Not tells of Senior High School Students Takashi (played Murakami Nijiro) who falls in love at first sight with a girl named Azusa (played Akari Hayami) and then they started dating.
One day, Azusa makes a strange confession by telling Takashi that everyone including his family would forget about him a few hours after the meeting.
At first Takashi do not believe what is said Azusa, but as time went on, Takashi began to realize that she began to forget the details of the time they spent together. Knowing this, he then made a note to document their time together so he does not forget. So what happens next?