The National Treasure Mikazuki Munechika is a slender signed , preserved at the Tokyo National Museum, and it carries the name of the smith the published sources place at in Kyoto in the late period and record as the founder of the school. A second of his designated blades counts him among the earliest smiths of the age in which the curved blade, the Japanese sword as such, took its settled form. The same source places him at in the capital around the Eien era and notes that under the name no Kokaji he "is widely known in popular lore". He stands at the head of the Ko-, the old Kyoto line with which the Yamashiro tradition begins.
His surviving work is very thin. Blades whose signatures can be accepted with certainty "are exceedingly few", and two practices are recorded, Munechika or . Two of the the published record describes in full are signed . A third, an recorded in Honma's inventory of the Imperial collection, is signed Munechika on the . Its commentary notes that blades signed Munechika "are exceedingly few" and that the work closest to it in the quality of the upper blade is "the celebrated Mikazuki Munechika". Because the Mikazuki is signed on the and this blade Munechika on the , the same text suggests that the style of the two may settle whether the smith who signs only is Munechika himself. Of the two Important Cultural Property , whose plates record a over , one is signed and the other bears a partly legible , attributed to Munechika. On the Mikazuki the two characters sit on the , centred above the of a -shaped . The carries its on the in somewhat thick, slightly large strokes, and the published sources state frankly that points in common with the Mikazuki inscription are hard to identify. That blade was transmitted at the Atago Shrine in Kyoto, where it is held to have been dedicated by Toyotomi Hideyoshi, and it appears among the sword drawings Kotoku sent to Ishida Mitsunari, so that its "value as historical source material is extremely high".
The fully described blades share one form. The Mikazuki and the are each a slender with strong , a high and a ; on the Mikazuki the curvature is especially strong at the , and on the blade it settles toward the point over a somewhat thin . The signed Munechika likewise has a high with and a tight . Their differ in emphasis. The Mikazuki is forged in mixed with a large grain tending to flow, with thick . The shows a tightly knit that looks slightly soft, laid finely and thickly, delicate , and a . The blade signed Munechika has a tightly knit with and here and there, its steel described as "a rather soft , truly moist and beautiful".
The is where the hand is most personal. On the Mikazuki it is a with small , the deep and plentiful, and along the edge runs a repeated chain of half-moon-shaped, -like in or . According to the Kyoho the name "Mikazuki was taken from the shape of the ", and the becomes a double line sweeping back in a slightly rounded turn. On the a narrow -toned temper carries a slight small with , while and run intermittently from base to point and break here and there into and , the double line continuing into the . The signed Munechika has a of deep with and frequent and ; in its upper half especially, -like activity and chains of form and , and the runs in and turns back with .
The published sources read this archaic activity as the core of his place in history. The low, small with doubled lines and intermittent "connects in one thread to the Shosoin pieces", and the work "is judged to be somewhat earlier in date than early Hoki and early pieces". The Mikazuki is described as an elegant blade that "shows a style of high dignity", and the commentary calls the Atago a work of archaic fragrance whose quality connects with it.
The Fujishiro appraisal places Munechika at Sai-jo , and the Toko Taikan values his work among the highest in its scale. Five designated works are on record: the Mikazuki, a National Treasure, two further designated Important Cultural Property and held by Nangu Taisha and Wakasahiko Jinja, the from the Atago Shrine, and the signed Munechika. That last blade was presented to the Emperor Meiji by the Sakai family, former lords of Obama in Wakasa, and is listed as in Honma's inventory of the Imperial collection. The Mikazuki, the published sources record, was counted "among the Tenka-Goken" in the period, was presented in the period to Tokugawa Hidetada as a bequest of Kodai-in, the wife of Hideyoshi, and descended thereafter in the Tokugawa shogunal house. None of these works is likely ever to change hands. They are patrimony kept in national, shrine and long-held care, and a privately held signed Munechika would be among the rarest things a collector of early Japanese swords could encounter.