"What, you can't see anything?" She questioned him in confusion. She again looked at the walls, there were many boxes now. Before she saw there was only one box. But there was a difference between them , the box which she saw before was having demonic creatures carvings.
"Alas!!! Now I remember, only you can see the black magic book. Other than you no-one can see it ," he replied . He came forward to her and said," Now don't waste your time and choose the correct book. You will have three chances , if you are able to pick up the right book then we are safe."
He knows all about this because he has already memorized the map. It was clearly mentioned that Yona will be given three chances to choose the correct black magic book otherwise the whole Dark Realm will get buried under Lava.