Among the swordsmiths said by old transmitted records to have worked in Ōshū (Mutsu and the wider northeast) from the Nara and periods through the age, the repeatedly observe that, of works actually surviving today, almost the only name that can be confirmed is (宝寿). The line is set within the Maikusa (Mokusa) sphere of Ōshū smiths, a group transmitted from the early period onward; one is described as a branch of the Maikusa smiths of Mutsu, and a entry pairs with Maikusa and, after , the Gassan group. The name itself was carried across a long span, from through and into the Ōei era, so that "" denotes a lineage rather than a single hand. A complicating thread runs through the corpus: one blade dated Enkyō 4 (1311) is signed Yamato--jū Tōmoto , raising the question of movement between Ōshū and Yamato, with the suggesting exchange of smiths through Shugendō mountain practice. Dated survivors anchor the chronology firmly, with inscriptions of Shōchū 2 (1325), Eiwa 2 (1376), Eitoku 2 (1382), and a run of Ōei years (5, 6, 12, 14, 22, 25).
The shared hand the describe is an archaic northern one. The forging is mixed with and , frequently with , the grain standing up () and at times an -like or, near the edge, tendency; thick gathers and bold enter, the steel inclining to a blackish tone with a whitish cast, and rising in the ground. The temper is built on and passing into , or a shallow joined with and ; the shows frequent , and run vigorously, and a -otoshi often drops the hardened edge at the . The tends to and , subdued and moist rather than bright, though certain pieces run brighter. The enters or with , and the carvings, over a sankō-tsuka-ken, are rustic yet carry an elegant taste. To recognize the hand, read the standing large-grained , the dark steel with whitish , and the quiet , set against the heroic form.
For , the diagnostic cluster is the combination of standing with bold , blackish steel under whitish , -otoshi at the base, and the subdued with , , and , the whole carrying a frankly provincial character that the treat as the lineage's signature. Signature study is itself a tool: the two-character of the Eitoku-era Imperial Household is read against an example dated Eitoku, certified an Important Art Object, to date later works by the chisel. Named survivors map the standing: two signed in the Imperial collection, the carrying a Kōchū of Kyōhō 7 (1722), the Shōchū 2 held by Mitake Shrine, and an transmitted as a hereditary treasure of the Murakami, the maritime warriors of the Seto Inland Sea. , signed, and dated , especially those not descending past early , the prize as reference material for an Ōshū tradition otherwise known largely through this one enduring name.