The Hoki school takes its name from Hoki province on the San'in coast, the northern slope of the country facing the Japan Sea, and it sits in the oldest stratum of the curved Japanese sword. Its founding figure is Yasutsuna, the representative master of Ko-Hoki (古伯耆), a smith the published sources place in the late Heian period, roughly contemporary with Sanjo Munechika and working at the moment the blade was passing from the straight chokuto into the curved tachi. Around him the commentary gathers a small founding circle, the Ohara group, named for the locality of Ohara: Sanemori, transmitted as Yasutsuna's son and the second master of the line, together with Aritsuna, Sadatsuna, Yasuie and Sanekage, a body that flourished from the late Heian into the early Kamakura period. Kunimune of Hoki carries the inheritance on toward the Kamakura age. Signed work survives at this depth of antiquity only in scattered numbers, most abundantly under Yasutsuna, so that the school is studied as much from the steel as from the inscription, and Yasutsuna's name itself approaches the legendary through the Meibutsu Dojigiri Yasutsuna.

What binds the members is a shared vocabulary the published records return to on blade after blade. The jigane is forged in itame mixed with o-itame and mokume, the grain standing open in large pattern, at times flowing into nagare-hada; thick ji-nie adheres, chikei enter, and patchy jifu with a jifu-utsuri or midare-utsuri drifts across a steel of darkish, iron-grey tone. Over that dark ji the temper rests on a suguha base broken into ko-midare, with ko-choji, ko-gunome and ko-notare mingling so that the whole pattern stays small in scale, the nie lying thick, the nioiguchi clouded into urumi and shizumi-gokoro rather than the clear bright line of Bizen, and kinsuji, nie-suji and sunagashi weaving insistently through the ha. The sugata keeps the archaic Heian silhouette, slender, with high koshizori and funbari, narrowing to a small kissaki, and many blades drop the temper above the machi in yakiotoshi, the boshi running straight to a small ko-maru or yakizume swept with hakikake. Within this common ground the members diverge by degree: Yasutsuna's midare runs larger and his upper hamon mixes ko-gunome and ko-notare in an independent form; Sanemori's pattern is smaller in scale and more archaic in tone, his signature cut in a long six-character mei; Sadatsuna divides into a rustic unsigned register and a finer signed one that brightens toward Bizen; Kunimune's best pieces break the upper edge into banded nijuba and sanjuba.

In kantei the recurring task is to hold Hoki apart from old Bizen, whose contemporaneous ko-midare it superficially resembles. The published sources draw the distinction on close view: where Ko-Bizen steel is bright and tight, the Hoki ji stands open and dark, the itame large and conspicuous, the nioiguchi clouded, and the kinsuji and sunagashi work through a softer, more provincial edge, what the commentary calls a rustic flavor carrying an ancient fragrance. A thread of Yamato spirit is read in certain blades as well, and Sadatsuna's o-sujikai yasurime link him toward Aoe even as the settled judgment keeps him in Ko-Hoki. The Aritsuna manner, the standing nie-laden itame with its small midare, is named among the acknowledged sources Masamune and Norishige took as their ideal in founding the Soshu tradition. Yasutsuna and Sanemori stand at the head of the school, Yasutsuna graded Sai-jo saku and his hand the working definition of Ko-Hoki, to which archaic unsigned blades gather as den attributions. Named works fix the standard, the Dojigiri Yasutsuna above all, alongside the kodachi bearing the added character Katsu and the carved tachi referenced to the Kishu Toshogu. Provenance runs through the houses that held the country, the Toyotomi, the Tokugawa, the Maeda, the Satake, the Shimazu and the Imperial line, with blades now resting in shrines and museums and a privately held example among the rarest encounters the field can offer.