User summary 変幻怪盗J　～ファントムダイヤの秘密～ (Hengen Kaitou J -Fantomu Daiya no Himitsu-) in English is 'The Everchanging Phantom Thief J -Secret of the Phantom Diamond-'. The 怪盗 (Phantom Thief) theme is quite popular in Japan, from Arsene Lupin or Lupin the Third, or recently, Persona 5 from the Persona series in console games. A card game with a phantom thief theme, the game has hidden role assignment. The cards are placed in a circle on the table, and the mission is to find the appropriate card in there. The Phantom Thief will win when the Heroine is found, or the Cops will win when they find the Phantom Thief. To win, you must control the Squad card moving on the circle of cards, and execute the "charge in" card at the appropriate position. Publisher's summary テーマは怪盗。テーブルの中央に環状に伏せられたカードの中から、怪盗役は「ヒロイン」カードを、刑事役は「怪盗J」カードを探しあてれば勝利です。 勝利条件を満たすには、伏せられたカードの上を移動する「機動隊」カードをうまく制御して、目的のカードの上に「機動隊」カードが来た時に「突入」カードを使います。