Kokoro is a first year middle school student. Or at least, she's supposed to be. A dark and very frightening experience has left her with a severe case of social anxiety that has her dropping out of school and shutting herself away from the world in her house, where she spends her days dealing with the guilt the disappointment in her parents eyes causes her.

One day, the mirror in her room begins to glow. Dragged into the other side of the looking glass by a little girl wearing a wolf mask, Kokoro there finds a fairy tale-like castle and six other children, all close to her in age. The little girl (who calls herself "Ookami-sama") tells them that the one who finds the Wish Key that is hidden within the castle will have a single wish granted. There are no rules, save for one: if they stay past 5 PM, the Wolf will eat them.

(Source: KiraKira Treasure Box)