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The Hozoin-Ryu Sojutsu (Hozoin spear-arts school), a school of martial arts, was founded in the late 1500s by Hozoin Kakuzenbo Hoin In-ei, a Buddhist monk at Kofukuji Temple in Nara, Japan.?

Along with the Hozoin school In’ei arranged the meeting between Kamiizumi Ise no kami Nobutsuna and Yagy? Sekishusai Muneyoshi, that became the catalyst for the creation of Yagyu Shinkage-ryu.

It is said that one evening, on seeing the reflection of?the crescent moon shining on Sarusawa pond, he was inspired to create a spear with a cross-shaped spearhead, which as a new dimension to the spear as it can now thrust, cut, and now pull, twist, catch, in a new dimension.
Historians say the spear was inspired by aboriginal Ainu bear hunters.

This article by David Lowry has more – The Spears of Hozoin.

Unfortunately, we know comparatively little of the Hozoin spear techniques. There is a Hozoin ryu still in existence, but its movements have been changed considerably. About twenty kata with the spear used in the manner of the Hozoin ryu are still extant, most of them featuring the school’s most distinctive technique. This involves thrusting the blade and tip of the spear toward the joints of an opponent’s body, at the knee, for example, or under the arm, and then twisting the weapon forcefully in a circular motion that bends the joint, throwing the opponent as neatly as any judo throw.