There's something in this world people have been longing for.
"Asteria" and "Esteria".
Two separate worlds.
They weren't supposed to be connected when a "gate" suddenly appeared, binding them together.
At first, both populations were confused, astonished, bewildered. After acknowledging each other's existence, if wasn't long before people were allowed to circulate freely across the gate.
Soon people became accustomed to one another.

The story takes place in Fuyuhi, a city covered with snow, where the main protagonist, Kouichi Sakurazaka, meets a girl. It was merely a chance.

However, this was the beginning of everything.
A pure white story, like the pure white snow...

[Translated from official summary]