This is part of the legend of the fight between Miyamoto Musashi and Sasaki Kojiro, supposedly the top Japanese swordsmen of their time, Kojira died. It's an illustration of the difference between bujutsu (martial technique/art) and budo (martial way). Bujutsu is only concerned with winning whatever the cost, regardless of honor or fairness, budo is about becoming a better person, so honor matters.
Judo (founder popularized this budo concept at the end of the 19th century), kendo, karatedo, aikido etc are budos, that's why those often appear as not being adapted to modern combat sports, their main goal is not winning combats.
Modern day bujutsu is basically western military training, learning to actually kill people with modern weapons and whatever dirty strategy you can employ, for example drones.