From the end of the Kamakura period into the Nanbokucho, the swordsmiths Unsho, Unji and Unshige worked at Ukan-no-sho in Bizen Province, a place name later also written Ukai. From their residence the line is called the Ukan or Ukai school; because every smith set the character Un, the cloud, at the head of his name, the published sources also know them as the Unrui. Unsho is named outright the school's "de facto founder"[[c:1]]. No dated work of his survives; the registers place the first generation around Kengen and Kagen (1302 to 1306), and his years are fixed through the dated blades of Unji in Showa, Bunpo and Kenmu. Tradition holds that he went up to the capital with Unji, learned forging from the Yamashiro smiths, and served the Emperor Go-Daigo as duty smith (後醍醐天皇の御番鍛冶); Honma notes the rare blades with a sixteen-petal chrysanthemum crest[[c:2]] below the habaki that lend the tradition weight. In the school's work "Yamashiro-style elements are intermingled within the Bizen tradition"[[c:3]], with no small influence from the Aoe school of neighboring Bitchu besides, so that the line is called "a distinctive presence among Bizen works"[[c:4]]. Fujishiro grades Unsho Jo saku.
The trait the judges name first is the curvature: a slender tachi with funbari at the base and a small point, arching evenly in a high wa-zori, the torii curve. The published sources observe that "whereas the Osafune work of the same period is koshizori, it presents wa-zori"[[c:5]]. He excelled in suguha, narrow to medium, mixed with ko-gunome, ko-choji and shallow notare. The ashi slant in reverse in the Aoe manner, and here and there wedge-shaped shadowy togariba enter. The nioiguchi tightens, carries ko-nie and at times sinks subdued; kinsuji and fine sunagashi run along the edge. Now and then the temper falls away slightly at the hamachi, and the published sources note that "the yakiotoshi at the base may be called Unsho's individuality"[[c:6]]. The boshi turns back round, ko-maru or tending larger; even of a blade steeped in Aoe character the published record observes that his particularity shows exactly where "the boshi does not point"[[c:7]]. The two-character mei sits toward the mune above the mekugi-ana, the character Sho set right of Un, his habit of hand; Honma takes the comparatively large mei of this type for the first generation.
The jigane is itame, in places knit to ko-itame or mixed with mokume, with ji-nie and fine chikei, and a midare-utsuri stands. Characteristically it is what the published sources describe as "the black jifu-utsuri peculiar to the Unrui, as if pressed in with the pad of a finger"[[c:8]], and the steel color besides tends somewhat blackish.
Honma counts it a point of interest that these late Kamakura Bizen blades carry nie in both ji and ha, at times with "an utsuri even more vivid than in Osafune work"[[c:9]]. The published sources state his range in one sentence: "his representative manners are two"[[c:10]]. In one, standing itame with mokume, ko-midare in the suguha with a reverse tendency, nie and sunagashi; in the other, closely knit ko-itame, the utsuri especially distinct, the suguha nioiguchi tight. The ubu tachi of Tokubetsu Juyo session 7 belongs to the former, with an old-toned utsuri as if pressed in with a finger[[c:11]]. Beyond the pair lies a stronger vein. "Unsho's manner is mostly low in temper and somewhat lonely in its activity"[[c:12]], yet other works are known with a somewhat wider yakiba, conspicuous ashi and yo and strongly attached nie, a make that connects to Unji; the folded-signature katana of Tokubetsu Juyo session 21 is read exactly so, his work at full power. At least two generations are recognized, the second placed around Bunpo or Kenmu; the registers transmit the first Unji as his son, or by another account his younger brother. Long signatures are exceptional: the tanto signed Bizen no kuni Unsho[[c:13]] is called a signature almost without parallel[[c:14]].
His position within Bizen is the published sources' own formula: the work of the line, beginning with its curvature, is reckoned "the closest to Kyoto work"[[c:15]] among Bizen products, and individual blades can be confounded with the Rai school or with neighboring Aoe. His suguha holds the Kyoto level while his ashi run saka in the Aoe way. Yet the clearly defined midare-utsuri keeps the flavor of his native tradition strongly present, and where the make breathes Aoe, the round boshi remains his own. The judges divide the kin by the temper: his yakiba mostly low and quiet in its activity, that of Unji wider and strongly nie-laden, with ashi and yo standing out. The more powerful of his own blades are read as approaching his successor; the line continues through Unshige.
Seventy-four designated works stand on record. Six are Important Cultural Properties, held as cultural patrimony, and nine more were designated Juyo Bijutsuhin before the war, among them a tachi counted one of the thirty-five blades hand-picked by Uesugi Kagekatsu[[c:16]], the ubu tachi of Iwasaki Koyata, now in the Seikado Bunko Art Museum, and the tachi passed from Tokugawa Iesato to the Sano Art Museum. Fifty-seven blades stand in the Tokubetsu Juyo and Juyo tiers. Signed works are comparatively numerous for so early a smith, thirty-eight signed against thirty-three unsigned here, nearly all the two-character mei. Ten blades carry recorded provenance: the Tokubetsu Juyo tachi of session 12 descends in the Uda Mori, a cadet line of the Nagato Mori; an Asano house katana carries a Hon'ami Kocho origami of 1676 valuing it at ten gold pieces; others passed through the Okochi house and the Imperial Family. The Important Cultural Properties and the museum holdings will not move. What a collector may realistically encounter is a Juyo blade, an osuriage katana attributed on the wa-zori, the dark jifu-utsuri and the saka-laced suguha, or one of the signed tachi; a signed ubu tachi comes to open hands only rarely, and is an event in the field when it does.
