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?
Out of the people close to us, the older 
ones departed one after the other,
Unter unseren Bekannten verließen uns
zwar nach und nach die älteren Leute,
Dans mon entourage,
Fra le persone a noi care,
Один за другим наши пожилые близкие
покидали этот бренный мир…