If you came looking for an answer to what the name Juuzou has to do with the king of diamonds, the deck goes A, 2, 3, 4, 5, 6, 7, 8, 9, 10, J, Q, K. Juuzou can be read with the kanjis of 10 and 3, 10+3 equals 13
I jumped from CMB to here. The logic jumps from conjectures are pretty wild here. King of spades represents Caesar, so brutus.... I think it's a pretty wide leap. At least the criminal fell for the trap so that the card was not critical.