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?
I ask that in one month's time, you please 
send him off to the site of the promise.
Ich wünsche mir, dass Sie ihn in einem
Monat an den Ort des Treffens schicken.
Dentro de un mes,
Dentro de un mes,
C’est dans un mois.
Fra un mese, ti prego,
Depois de um mês, gostaria que
o enviasse ao lugar marcado...
Пожалуйста… направьте его через месяц
в обещанное место.