A katana now in Osaka, designated at the fourteenth Jūyō session in 1966, is judged in its commentary to be "sound in both ji and ha and thought to represent Sukemune's finest work"[[c:1]], and it gives the measure of the man. Sukemune is, with the mainstream Yoshisuke, one of the two principal names of the Shimada school of Suruga Province, a Muromachi workshop on the Tōkaidō between Mino and the late Sōshū hearths. The published sources place him as the younger brother of the founder Yoshisuke in the mid-Muromachi period, and the name carried that standing through several generations down into the shintō era. The reference works arrange those hands across a long run, citing Sukemune work as early as the Bun'an and Bunki eras and then a Sukemune of the Tenbun era, so the name spans the whole Muromachi century. Because the signature style does not separate the generations either, a signed Sukemune is read for its workmanship rather than assigned a number, and the date inscriptions, where they survive, do the work the mei cannot.
His characteristic hand is the connected gunome that the published sources name the school's own. Over the itame the temper is a gunome run together in series, crossed with gunome-chōji and pointed togariba, at times rising into a box-shaped notare about the koshi, abundant nie lying through it with tobiyaki, kinsuji and sunagashi, the nioiguchi bright. Of the long katana designated in 2020 the NBTHK writes that "the hamon features the Shimada school's hallmark of connected gunome"[[c:2]] and reads its bright nioiguchi, kinsuji and sunagashi as "features that strongly express the characteristic manner of Sukemune"[[c:3]]. The boshi follows the midare, running midare-komi to a ko-maru with hakikake, on the largest blade strongly covered in nie and tending toward nie-kuzure. This is the manner the published record ties to the late Sōshū smiths, to late Seki and to the Senju group, and reads as close to the work of Mino and Ise.
The jigane is the steady foundation beneath the ha. The forging is an itame, well knit and at times dense, that overall flows and leans toward masame, ji-nie lying through it and chikei entering, with a tendency toward hada-dachi where the grain stands open. On the 2020 katana that jigane is described as a tightly forged itame, partly flowing and tending toward masame, the ji-nie finely granular yet densely applied and the chikei clearly visible, a Suruga reading of the Sōshū surface rather than a tight Bizen jigane. It is on this flowing, slightly standing steel that the nie activity of the edge is laid, and the finest of his blades are praised for the clarity that results, the bright nioiguchi and the streaming kinsuji and sunagashi together.
The designations show the Shimada shop's range of form. Four of the five with commentary are shinogi-zukuri katana, several with strong sakizori or a tachi-like koshizori, one of them an eighty-centimetre blade of robust, tachi-like make rich in hataraki; the fifth is a hira-zukuri tantō of orthodox, curvature-less form. On that tantō the manner shifts to the school's other register, a suguha mixed with small gunome over a flowing itame, sunagashi and kinsuji appearing, which the published sources read as work "made with an eye toward the manner of Shizu"[[c:4]], appraising the piece as older than the Tenbun Sukemune of the meikan. His horimono are a school feature carried with skill, bonji, a grass-script kurikara, a clawed ken, futasuji-hi closed with maru-dome and gomabashi, which the commentary ties to Muromachi carving in general and to the work of the Shimohara smiths.
What distinguishes Sukemune is best drawn from his own grounded traits. His is the connected gunome in abundant nie, with kinsuji and sunagashi over a flowing, masame-leaning itame, a provincial Suruga reading of the late Sōshū idiom that the published sources set beside Mino and Ise work; the Shizu-leaning suguha of the tantō is the deliberate exception, and the prominent horimono is the mark of the broader Shimada shop, shared with Yoshisuke and Hirosuke. Where a generational verdict is impossible the commentary turns to the blade, calling the Osaka katana the finest work of the name and reading the Eiroku-dated katana as a superior piece whose inscription, the published sources note, "is of particular value as documentary reference material" (永禄年紀は資料的に貴重である) for fixing one hand within the long run. The last of his katana drew the further observation that, though signed on the sashi-ura in the manner of a tachi, it should be understood as an uchigatana, a reading the NBTHK reaches from the position of the mekugi-ana and the overall sugata.
Sukemune's designated record is modest in scale and entirely signed, five of his blades holding the Jūyō rank with his record reaching no higher tier, so his work is encountered as Jūyō and lower-ranked pieces rather than as patrimony held permanently out of reach. He carries a Tōkō Taikan value of 450 monme, a solid provincial standing rather than a first rank, in keeping with a respected one-province name. One blade of his is recorded in Imperial provenance, the kind of holding from which a Shimada work rarely returns to circulation. The number of designated works on record is small, and across the run of generations under one undivided name a securely fine example, of the soundness in ji and ha that the published sources praise in his Osaka katana, is the thing worth waiting for. Such a blade comes to market only from time to time, and when one does it is a good representative of a provincial school whose hand sits close to the late Sōshū tradition.
