Walk into almost any karate tournament and you will see competitors throwing punches to the face, earning points for light, controlled contact, then bowing politely at the end. Walk into a Kyokushin tournament and the experience is different — bodies absorb full-power kicks to the ribs, sweeps send fighters to the floor, and a match can end in a knockout. Yet hand techniques to the head are completely banned. No headgear is worn in adult knockdown divisions. Points are not awarded for strikes; only knockdowns and superiority matter. To an outsider, it can look chaotic. To anyone who understands...