While struggling to make friends after his parents’ divorce, Koyomi Takasaki meets Kazune Takigawa, but apparently, they already have. Kazune reveals that she’s from World Line 85, an alternate universe in which she and Koyomi are lovers. But in a reality where moving between dimensions is natural, could Koyomi be the one from another world?
The Koyomi I know is more 
put-together and dependable...
Mein Koyomi ist selbstsicherer
und man kann sich auf ihn verlassen.
Mi Koyomi es más responsable
y se hace cargo de las cosas.
Mi Koyomi es más responsable
y se hace cargo de las cosas.
Le mien est beaucoup plus réfléchi,
c’est quelqu’un de fiable !
Il mio Koyomi è un tipo più deciso e affidabile.
Meu Koyomi é mais firme
e posso contar com ele.
Вот мой Коёми и умнее,
и гораздо надёжнее!