Among the ruins of the city, there is a game only children can play. It is called “Otokoyo”; a game of hide-and-seek. But whenever children play this game, one by one they would disappear into the blinds of the buildings… The story begins when a boy enters the world of Otokoyo, to find his missing sister.

[Source: Anime News Network]

This dream...
I just can’t put a name to it.

A girl tormented by nightmares writes down her dreams and names them, hoping to never forget her fears. But one day, a nightmare she couldn't name transforms into a monster and spreads across the world, plunging it into chaos.