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?
Perhaps her previous prank 
hadn't been enough,
Vielleicht hatte ihr die Rache letztens nicht
gereicht oder sie wollte sich mit mir messen.
No sé si no tuvo suficiente,
No sé si no tuvo suficiente,
Comme si sa blague
n’avait pas suffi,
Forse non le era bastato lo scherzo di prima
Não sei se ela não estava satisfeita
com a brincadeira anterior,
Видимо, ещё не расквиталась со мной,
и потому старалась во всём состязаться…