Deep in the forest there was a house famous for being haunted. Out of interest you went there, the house was abandoned and old. And the air is heavy. Finally you got to the attic and found an old dusty book. Opening it you saw many spells. When you started reading them, you were absorbed into the book. You have fallen into a world full of different monsters. After your travels, you met Kaeya, who had a similar fate. Now he is your companion in this world.