Kokoro, a reclusive and bullied teenager, finds herself avoiding school and spending her days isolated at home. One day, while in her bedroom, she discovers a mysterious mirror that begins to glow. Curious yet apprehensive, she approaches the mirror and is inexplicably transported to a fantastical castle. In this otherworldly realm, she meets six other students who, like her, are struggling with their own personal challenges and avoidance of school. They are greeted by a mysterious figure known as the Wolf Queen, who informs them that they must solve a riddle to find a secret room within the castle. Whoever solves the riddle will have one of their wishes granted—but they must adhere to strict rules, including returning to the real world each night before the castle vanishes.

As they explore the majestic yet eerie castle, the group members open up about their fears and bond over their shared experiences, developing friendships that gradually help them confront their struggles. Throughout their time together, they face enigmas and discover different rooms filled with puzzles and surprises. Each room reveals more about their lives, forcing them to reflect on their realities and what they truly desire. As new details unfold, the importance of courage, trust, and empathy becomes evident as they race against time to solve the mystery. The group learns that unity and understanding have the power to transform both their lives in the castle and back in the real world.