In a neighbourhood in Tokyo, seven young people wake up to find their bedroom mirror's shinning. Placing their palms on the surface, they are pulled through into a wondrous castle, where they encounter not only each other, but also their taskmaster: a bossy young girl in a mask, named Wolf Queen.

Though they don't know it yet, they all have one thing in common. Eager to uncover the secret of the castle while keeping their own, their time here will not be without glitches. For a start, each day they must leave by five o'clock or face a terrifying penalty; they must all hunt for a key that will grant only one wish; they must tell no one about their experience.

As they struggle to abide by the rule of the game and each other's emotion boundaries, a moving story unfolds, of seven characters trapped in a cycle of misunderstanding and loneliness, who are ultimately set free by the power of friendship, empathy and sacrifice.