In a tranquil neighborhood of Tokyo, seven teenagers wake to find their bedroom mirrors are shining. At a single touch, they are pulled from their lonely lives to a wondrous castle filled with winding stairways, watchful portraits and twinkling chandeliers. In this new sanctuary, they are confronted with a set of clues leading to a hidden room where one of them will be granted a wish. But there's a catch: if they don't leave the castle by five o'clock, they will be punished. As time passes, a devastating truth emerges: only those brave enough to share their stories will be saved.

Kagami no Kojou was published in English as Lonely Castle in the Mirror by Doubleday on April 22, 2021.