Yukiide Kaoru is in charge of the Labyrinth Game at the Metropolitan Police Department, a duty that previously belonged to his father. At age 12 he was diagnosed at twelve with encephalitis lethargica or "Sleepy Sickness". His condition worsened at age 15 and because of that, he lost 10 years of his life in a coma. He awoke 2 years before the game with Kaji Takaomi, completely changed and enslaved by his father's ideals of order.