"A world" - After graduating from a
university, close friends Takashi Tsuruga (Yuta
Tamamori) and Tomohiko Miwa (Shota Sometani)
begin work at a company which does brain
research. One day, Tomohiko introduces Mayuko
Tsuno (Riho Yoshioka) as his girlfriend.
Takashi is stunned. When he was a university
student, Takashi saw Mayuko Tsuno everyday on
the train opposite from the one he rode. He
became attracted to her back then.
"B world" - When Takashi Tsuruga wakes up,
his girlfriend Mayuko Tsuno makes breakfast as
usual at his apartment. His friend Tomohiko
Miwa introduced him to Mayuko and they have
lived happily as a couple. Everything seems to
be going smoothly, but Takashi begins to have
doubts. Tomohiko, who worked with him at the
same company, disappears and he can't discern
if his memory is real or imaginary.