Nagamine Tomoki is a second-year student at Kazamizaka Academy.
Because his parents work abroad, he’s been staying at the home of his childhood friend Minagawa Yuuhi ever since he transferred here.
He lives a peaceful student life, participating in the library committee and helping out at Yuuhi’s family business, the Yuugaotei cafe, after school.

Until one day.
Tomoki stops by a used bookstore called Fuurindou, near the shopping district, to look for a book recommended to him by Ayase Sayuki, the chairman of the library committee and an upperclassman he admires.

Tomoki isn’t surprised to find the interior of the store a match for the deteriorating exterior. The air is humid, the bookshelves are black with dirt, and the many books are covered in dust. Even so, it would be a shame to leave without at least a look around, so he goes hunting for the book he’s after.

He wanders around the shop for a little while, casting his eyes about until a certain book catches them. On that back of that old book are the words “your diary”.

Strangely curious, he picks it up, turns it over to the cover, and——
A girl pops out, in a wash of warm light.

“Are you Yua’s new friend?”

After he meets Yua, the strange girl who claims to be a god, destiny begins to move for Tomoki—and for the girls around him. And for a little white diary——