Shuffle! I-KAI Defend Game

AU. Yuugi's classmates think he's insane, his family walks on eggshells, and no matter what the doctors try, they can't stop his hallucinations. When the fabric separating two worlds begins to fray, he solves the Millennium Puzzle, tying his fate to that of another world. He must play the game as a neutral party stuck between two dimensions, but where does the true danger lie?