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Ko-Aoe (Senoo smiths, Bicchu) · Bitchu · around 1213-1219
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Masatsune is a Ko-Aoe smith of Bitchū, working from the end of the Heian period into the early Kamakura, and the published sources name him the representative smith of the Senoo line. Following the Genki Mekiki-sho and the Kokon Meizukushi, they divide the old swordsmiths of Bitchū into the Aoe smiths, who as a rule sign with the character Tsugu, and the Senoo smiths, who descend from Noritaka and forged at Senoo, east of Aoe toward Bizen. Among the Senoo hands (Koreshige, Yasuie, Hirotsune, Tsunemasa, Moritsune, Yukimasa) Masatsune alone survives in some number: his examples "are not few, while extant works by the other smiths are rare"[[c:1]]. The Meikan enters the first-generation Ko-Aoe Masatsune in the Ken'ei era, yet extant blades descend no later than the early Kamakura, and the sources add that more than one smith seems to have used the name, with a range of signing manners.
His recognized blade is the slender tachi of classical, graceful shape, high in koshizori with pronounced funbari, several still signed with the two-character mei. The temper is a quiet one: a chū-suguha or narrow suguha base into which ko-midare and small ko-chōji enter, with ashi and yō well inside, ko-nie well attached, and fine kinsuji and sunagashi in places. The nioiguchi is at times tight, but the published sources state the usual case plainly: "in most, compared with Ko-Bizen, the nioiguchi is somewhat subdued and the grain stands"[[c:2]]. The bōshi runs straight and turns back in a small ko-maru, now and then narrowing toward a yakizume-like finish. Read against the Ko-Bizen Masatsune it resembles, his work is called "somewhat plainer, with an astringent, subdued taste"[[c:3]].
The jigane carries the Bitchū character. He forges a ko-itame, well packed on the finest blades, standing a little in places and mixed with mokume, with ji-nie and fine chikei. Through it run the speckled jifu that the sources call chirimen-hada, at times with clear sumihada, and a jifu-style or quiet irregular utsuri rises. The tang is filed in ō-sujikai, and the sources state that on the Ko-Aoe Masatsune the filing is always ō-sujikai. These three points, the crepe-like jifu, the mokume in the forging and the original ō-sujikai filing, are the ones the newer designations name again and again as the marks of the Senoo Masatsune.
The resemblance to Ko-Bizen runs close enough that the sources concede that "among them are works almost indistinguishable from Ko-Bizen"[[c:4]]. Several tachi show how the question is settled: each looks at first sight close to Ko-Bizen Masatsune and is re-read on the evidence of its jigane and original filing. One of them carried an origami by Hon'ami Kōyū of the Genbun era for the Bizen Masatsune, and at its Tokubetsu Jūyō designation the sources conclude that it "is properly judged the Bitchū Senoo Masatsune"[[c:5]]. The signature, too, is placed on either face, the haki-omote or the haki-ura, where the Senoo smiths otherwise favour the tachi-mei. Beside the signed tachi stand the ō-suriage mumei katana attributed to him, judged by the same jigane, quiet suguha and ko-maru turnback. The dating the sources leave open: because the name passed through several hands and extant works run earlier than the Meikan's Ken'ei date, one signed tachi was designated as a blade merely bearing the signature, the question deferred to future study.
Within the Senoo line he is its representative and the one whose hand is most often read. The published sources call his work "archaic and deeply flavored"[[c:6]], preserving the refined bearing of the transition from late Heian to early Kamakura, and on one ubu signed tachi judge it "the most archaic in character among works of this name"[[c:7]]. Of a later Jūyō tachi they write that it is "a truly archaic blade, with a moist quality in the jigane and hamon, and of high dignity"[[c:8]], and they name a tachi at Tsurugaoka Hachimangū as the typical work of the smith.
His record is fuller than the old view of a rare name allows. Twenty of his blades stand in the Tokubetsu Jūyō and Jūyō tiers, four of them Tokubetsu Jūyō, of which two are called especially well made among his works; three more were designated Jūyō Bijutsuhin before the war, one signed tachi, which the entry judges Ko-Aoe as tradition holds, is recorded in Honma's inventory of the Imperial collection, and the Tsurugaoka Hachimangū tachi, dedicated to the shrine by the shogun Tokugawa Yoshimune, is a National Treasure. Six further signed tachi, their plates dating them to the Kamakura period, are Important Cultural Properties, held among others by the Kumano Hayatama Taisha, the Takisan Tōshōgū and the Shirotori Jinja. Several retain their original tang and signature, which the sources call "especially valuable for remaining ubu and signed"[[c:9]], and one Jūyō tachi they name "one representative work of Ko-Aoe Masatsune"[[c:10]]. One kodachi was formerly held by the Arisugawa-no-miya princely family, and a Tokubetsu Jūyō tachi survives in an early-Meiji handachi mounting with fittings by Fuchikawa Kazunori. Most of these blades are held rather than traded, and a signed Senoo Masatsune comes to market only seldom; a privately held example remains a notable thing for a collector to encounter.
Where Masatsune stands among comparable artisans: across all of nihontō, and within tradition, era, and period. The tiers (Foremost · Leading · Major · Notable) weigh official designations from the NBTHK and Japan's Agency for Cultural Affairs, together with historical honors of lasting repute such as the Sansaku and Meibutsu-chō.
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Bizen-den · Bitchu
Phase: Ko-Aoe古青江· 1100–1235
20 pieces on the market now
The Ko-Aoe school flourished in the lower basin of the Takahashi River in Bitchu Province, forging swords at the districts of Koi and Manju in a region long renowned as a source of iron. The school is traditionally held to have begun with Yasutsugu around the Joan era (1171-1175), and works produced from the end of the Heian period through approximately the mid-Kamakura period are distinguished as Ko-Aoe, with production continuing under the broader Aoe designation through the late Nanbokucho era. The representative smiths of this early lineage -- Yasutsugu, Moritsugu, Sadatsugu, Tsunetsugu, Kanetsugu, Toshitsugu, Suketsugu, Tametsugu, Shigetsugu, and Tsugutada among them -- share the character "tsugu" as a common element in their names, forming an unusually cohesive dynastic identity. A distinct sub-lineage, the Senoo group, stood apart from this main line: led by Masatsune and Yukizane, the Senoo smiths forged to the east toward Bizen and rarely incorporated the "tsugu" character. " The Ko-Aoe technical vocabulary is remarkably consistent across its many smiths. The kitae is built on itame-hada intermixed with mokume, the grain standing conspicuously to produce chirimen-hada -- the tightly compressed, crepe-like surface texture that is the school's most recognizable trait. Patches of jifu and ji-madara mottle the ground steel, while fine ji-nie adheres thickly with chikei interwoven; a dark-toned sumi-hada may appear amid the standing grain. Utsuri manifests in several forms across the school's corpus: midare-utsuri, jifu-utsuri, and in certain works by Tsunetsugu, tiered bands suggestive of dan-utsuri. The hamon is predominantly suguha-based, mixed with ko-midare, ko-choji, and ko-gunome; ko-nie adheres well, and fine kinsuji and sunagashi run through the hardened edge, while the nioiguchi characteristically tends toward shizumi -- a subdued, sinking quality -- or in certain smiths appears bright and clear.
The boshi typically turns in ko-maru, sometimes with hakikake. Tang conventions provide critical diagnostic markers distinguishing Ko-Aoe from contemporary Ko-Bizen: bold o-sujikai file marks, deeply cut machi, and signatures placed on the haki-ura side in characteristically thick chisel work. The NBTHK consistently observes that compared with Bizen works of the same era, Ko-Aoe productions "convey a somewhat quieter and more subdued taste" -- the restrained, astringent shibui character that defines the school's aesthetic. Yet within this disciplined restraint, individual members demonstrated striking range. Yasutsugu's most celebrated tachi -- transmitted as an heirloom of the Shimazu family and counted among the legendary Tenka Goken -- displays a flamboyant midare-ba of extraordinary vitality that rivals anything produced in the Bizen tradition, while Sadatsugu's finest works invite comparison with National Treasure-class examples. The later Osumi no Gon no Suke Sadatsugu developed a bold personal manner, broadening the yakihaba, concentrating nie to produce shima-ba-like scenery, and tempering the boshi with deep kaeri -- features that overflow with vigor. Kanetsugu is praised for almost no unevenness of workmanship across his corpus, while Moritoshi's forging is singled out as tighter and better refined than is typical even within this exacting school. The Senoo branch, represented by Masatsune and Yukizane, carried a flavor somewhat resembling Bizen work while maintaining the characteristic chirimen-hada and o-sujikai file marks that identify the hand as unmistakably Bitchu. Across its full productive span, the Ko-Aoe school stands as one of the foundational pillars of the Japanese sword tradition: a lineage whose refined suguha aesthetic, distinguished crepe-textured forging, and quietly astringent taste secured Bitchu swords their ancient reputation and continue to command the deepest respect in the study of classical swordsmithing. Learn more →
| Smith | Era | Designated |
|---|---|---|
| Tsugunao次直 | 1345-1361 | 26 |
| Masatsune正恒 | 1213-1219 | 31 |
| Naotsugu直次 | 1288-1350 | 20 |
| Yasutsugu康次 | 1211-1213 | 10 |
| Kanetsugu包次 | 1211-1213 | 9 |
Bizen in the Kamakura period
Kamakura was Bizen’s summit. Tradition places Ichimonji smiths among Go-Toba’s goban kaji, Mitsutada founded the Osafune line at mid-century, and orders flowed from the court and the warrior government alike. No province holds more National Treasure blades.
Certifies a genuine blade worth preserving: a signature confirmed correct, or, if unsigned, an era, province, and school that the NBTHK can reliably identify.
The NBTHK (Nihon Bijutsu Tōken Hozon Kyōkai, the Society for the Preservation of Japanese Art Swords) is a public-interest incorporated foundation founded in 1948 and supervised by Japan’s Agency for Cultural Affairs (Bunkachō); it is based at the Japanese Sword Museum in Tokyo. Its expert panels physically examine each submitted work (shinsa) and issue a certificate (kanteishō) ranking it by artistic and historical merit. NBTHK papers are the most widely recognized standard of authentication for Japanese swords and fittings.
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