Koryu, literally 'old flow from the past,' refers to Japanese martial traditions that predate the sweeping cultural changes that followed the Meiji Restoration of 1868. They generally have a very different character and tone from modern martial arts, such as kendo, judo or aikido which followed. More than the study of antique weapons, self-defense or a form of athletics, these martial traditions are a cultural legacy and a window to another time and place. In the first edition of Old School, Ellis Amdur, a renowned martial arts researcher, and himself an instructor in two different surviving...