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?
In each individual world, each 
individual me loves Kazune.
In allen möglichen Welten
lieben alle möglichen Ichs dich, Kazune.
Dans chaque monde,
mes moi sont amoureux de toi.
In ogni singolo mondo,
В каждом из миров…