Judai just gave a speech about how there’s one card in everyone’s deck that holds all of their happiness, anger, and sadness that they’ve shared with each other in their memories as they’ve dueled. And Judai just drew the one card that represents that for him. He’s made many friends through this card, many precious fond memories, and unfortunately many bad ones too from his crimes in Dark World. But it will give him the strength he needs to win this duel for the future.