A katana dated Bunkyū 2 (1862), made in his forty-fifth year, is singled out by the published sources as an especially outstanding blade in the Bizen manner he favoured, the clarity of both ji and ha splendid. Its maker, Ishidō Unju Korekazu, was born in Yonezawa in Dewa and known by the common name Masatarō. He was a nephew of the Yonezawa domain smith Katō Chōunsai Tsunatoshi and first learned forging under him. He then became the son-in-law of the sixth Ishidō Korekazu and succeeded as the seventh head of the Edo Ishidō house, dying in Meiji 24 (1891) at the age of seventy-five. His working life ran from the closing years of Tenpō into early Meiji, and comparatively many of his works survive. The published commentary counts him among the leading masters of the Shinshintō period, standing shoulder to shoulder in skill with Jirōtarō Naokatsu and Hosokawa Masayoshi.
The published sources describe his hand through a method rather than a motif, and they state it in nearly the same words entry after entry. His work divides broadly into two modes, Bizen-den and Sōshū-den, but his true forte was the Bizen chōji that may be called the hereditary specialty of the Ishidō house. Whereas many Shinshintō smiths working in the Bizen manner tempered their chōji in nioi-deki, Korekazu tempered his in nie-deki, and the commentary concludes that "in this one can discern his originality"[[c:1]]. Two entries put the reputation in a phrase: he is the smith described as having "tempered Bizen-style chōji-midare in nie"[[c:2]]. One entry also gives the development behind it. His early works, like those of his teacher Tsunatoshi, show a tight nioiguchi and a chōji-midare with ashi; in later years he tempered this chōji in small nie, which the source says brought a further degree of variation into the ha[[c:3]].
On the typical blade the chōji is mixed with gunome, ko-chōji, ko-gunome and slightly pointed elements. The ashi enter long and frequently, the nioi is deep, and the nie lies thick, with patches of coarser nie that leave the temper a little uneven. Sunagashi runs through the ha on about three of every four of his blades, often joined by kinsuji and nie-suji, and the nioiguchi is bright and clear. The jigane is a tightly forged ko-itame, at times mixed with mokume or flowing grain. Its ji-nie lies in a fine, thick cover with fine chikei entering frequently, and where it packs hardest it approaches a muji-fū surface. One entry singles out this forging as especially strong even within his own work[[c:4]]. The bōshi runs midare-komi to a ko-maru, often with hakikake, and one entry finds in its handling the mannerisms of Tsunatoshi, from which it infers a stylistic tie between the two smiths. The blades are robust ubu katana, wide in body with thick kasane, the point a long chū-kissaki or an ō-kissaki, the tang finished with ō-sujikai file marks and a long signature.
Beside this Bizen core the published sources record other registers. Korekazu, one entry notes, himself claimed a proficiency in Sōshū-den[[c:5]], though most of his finest works are Bizen. A daishō of Ansei 2 (1855) succeeds in the Sōshū manner and comes with a formal rō-nuri kamishimo-zashi mounting whose full set of fittings is by Yokoya Sōju. A gassaku katana with the Aizu smith Kakuda-suke Gengō, his exact contemporary, records that Gengō forged the blade and Korekazu applied the temper; the judges found that it seems "entirely the work of Korekazu"[[c:6]]. The rarest face is suguha. A long, robust katana of Ansei 5 (1858) over a muji-fū forging carries a suguha-based temper with gunome, deep in nioi with a bright nioiguchi, and the source calls it "a comparatively gentle style" for him[[c:7]].
The record keeps returning to the same blades as his measure. Of one Juyo katana, whose ko-itame carries dust-fine thick ji-nie and whose temper shows kinsuji and nie-suji with unusual vigour, the commentary writes that it is "a blade in which the true specialty of Korekazu is brought forth without reservation, demonstrating an exceptionally distinguished workmanship"[[c:8]]. Other long blades with ō-kissaki are praised for holding together without strain despite their length. His work also carries the marks of its moment. One katana is carved with the characters printed in the source as 「譲夷」, a carving the entry reads as showing the temper of the age. Another was made for Sanada Kōkan, a retainer of the Sendai Date house, and its tang carries a verse in man'yōgana: 「この太刀に貯めし心は身一つよ, 守るたまかは我が君のため」 ("the heart I have stored in this tachi is but one: to protect, indeed, for my lord").
Fujishiro grades him Jō saku, and the Tōkō Taikan values him at four hundred. He has no National Treasure and no Important Cultural Property. Twenty-four of his katana are designated Juyo, at sessions from 1964 to 2022, and a twenty-fifth, a katana dated Kaei 6 (1853), is recorded in Honma's inventory of the Imperial collection. That entry adds a note of regret: his was the era of the Meiji sword ban, and "it is regrettable that he could not fully exercise his skill"[[c:9]]. All of these blades are signed, and most are dated. Because comparatively many survive, a signed, dated Korekazu katana comes to market from time to time rather than once in a generation, and a sound example in his nie-deki chōji is among the more attainable ways to hold the late Bizen revival at its most personal.