Koshin-ryu

Koshin-ryu is a style of swordsmanship that originates from, and is practiced within Wano Country. Its current formal successor is Gozen Shizuka. The fighting style seeks to pass on what the founders preached as the "truth of steel" (鋼の真実, hagane no shinjitsu), an answer to swordsmanship that can only be found by swordsmen through discipline and training.