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?
so they suffer the pain of that
 sadness over and over.
und man leidet immer
wieder an dieser Traurigkeit.
así que la tristeza
nos asalta nuevamente.
así que la tristeza
nos asalta nuevamente.
et continuent à souffrir
de ces mêmes regrets.
e continuano a soffrire 
per colpa di quella stessa tristezza.
e sofrem várias vezes por essa
mesma tristeza e sofrimento.
Поэтому и остаётся годами
вспоминать свою глупость.