Kaito Daimon, a genius at solving puzzles, is given a strange device and receives an invite to solve a dangerous puzzle inside some ruins. Going with his friend Nonoha Itou, he makes his way through the strange maze, managing to find a secret solution thanks to Nonoha's help. Arriving at the center of the maze, Kaito finds a strange bangle known as Orpheus, which attaches itself to his arm. After this happens, the room they are in is sealed off, and Kaito is given a puzzle in which he is told to pull a correct lever to stop the pillars holding the ceiling up breaking apart. As Kaito reaches wit's end, the bangle on his arm glows and Kaito enters a state where he becomes able to see the puzzle's solution.