Sora was a model high school student promised a bright future. But one day, while he was in class, an intense drowsiness took hold of him. Unable to fight against sleep, he dozed off for a few moments. When he woke up, he was astonished to find that all his classmates and his teacher had mysteriously disappeared. He was now alone facing an enigmatic man, dressed in a butler's costume and sporting a black mask that contained a most terrifying smile, named Gabriel. Instead of killing him, Gabriel sent him to the catacombs, a dark world where ten trials awaited him.