Niten Ichi-ryū

Niten Ichi-ryū (二天一流^?), which can be loosely translated as "the school of the strategy of two heavens as one", is a koryū (ancient school), transmitting a style of classical Japanese swordsmanship conceived by the warrior Miyamoto Musashi. Hyōhō Niten Ichi-ryū is mainly known for the two-sword—katana and wakizashi—kenjutsu techniques Musashi called Niten Ichi (二天一, "two heavens as one") or Nitō Ichi (二刀一, "two swords as one").

Around 1640, Musashi intended to pass on his art to three successors from among his thousand students; specifically, to Terao Magonojo, his younger brother Kyumanosuke and to Furuhashi Sozaemon. He considered Magonojo to excel in technique but to lack in reflection, while Furuhashi excelled at reflection but lacked technique. Magonojo received the treatise, the Go Rin no Sho, on the condition that he read it and then burn it. But Furuhashi borrowed it for a few days and on the orders of Hosokawa Mitsuhisa made two copies- one for Hosokawa and one for himself, which he transmitted under the name of Ihon go rin no sho. The best known edition today is the Hosokawa copy.