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?
Did we have a fight 
the last time you came over?
Haben wir uns gestritten,
als du letztens hier warst?
Мы разве ж ссорились,
когда ты в прошлый раз приезжал?