Hokushin Ittō-ryū (北辰一刀流) was created by Chiba Shūsaku Narimasa (千葉周作成政), who trained in Ittō-ryū before going to Edo and combining it with his family’s Hokushin Musō-ryū (北辰夢想流) into a new method. His reputation rested on a rationalized pedagogy — ji-ri itchi (事理一致; “unity of technique and principle”) that paired kumitachi (組太刀; paired forms) with shinai sparring, and a streamlined curriculum — by which a student could reportedly accomplish in five years what other schools took ten to teach.
The school produced many of the celebrated swordsmen of the period and exerted a lasting influence on the development of modern kendō. Chiba Shūsaku (1794–1856) opened the Genbukan (玄武館) in 1822 at Nihonbashi Shinagawa-chō, later moving it to Kanda Otamagaike; the largest and most famous of the three great Edo dōjō (with Saitō Yakurō’s Renpeikan and Momonoi Shunzō’s Shigakukan), its instruction in his final years fell to his gifted second son, Chiba Eijirō (千葉栄次郎).
Hokushin Ittō-ryū survives in several lines (including the Mito Tōbukan tradition and the Konishi / Genbukan line) and is comparatively well served by English-language sources.
