In 1920, the Choson Chaeyukhoe (Choson Athletics Association) was established, and a year later, Kang Nak-won opened Choson Mudogwan, the country's first private school to teach Kumdo exclusively. Japanese Military sword was also reinforced by the efforts of Japanese sword master Nakamura Taisoburo who was stationed in Manchuria at this time. Drawing on the calligrapher's repeated practice of the character "Ei" with its eight basic strokes, Nakamura develops "Ei-Ji Happo" (literally: "8 Laws of the Character Ei ") as a drill for practicing the basic cuts and thrusts of his sword material. This would later be formalized into "Happo-giri" (literally: "Eight Directions of Cutting") and become an integral part of his style, Nakamura-Ryu Batto-jutsu.