When the characters keep saying there's a "safe strategy" in a gambling manga, you just know there's going to be a wrinkle that exploits it. People have been speculating something with the timer and the new year, I wonder if Baku could exploit that to cause the penalty. If he explicitly told Yakou to pick the handkerchief game, he might understand the basics of the game (and know enough about Yakou to conceive of how he would construct the game). I'm not sure if that was his exact plan going in, I think he had put Kaji there to cast doubt on literally anything in the tower, but even if he didn't come in expecting to use that timer, he could certainly find an opportunity to exploit this opening...he was able to grasp Sadakuni's cheating and manipulate the game into falling directly on his blind spot at the most crucial time after all.
Yakou's hand is already coming apart...CPR does require a large amount of force to be done properly. You have to wonder if at some point he won't be able to revive them anymore.
Very, very weird to see Souichi this rattled.