The name Masatsugu is borne by smiths of markedly different traditions and eras. The earliest is Ko-Bizen Masatsugu, recorded in the meikan only as "Genryaku" (late Heian period). Because he prefixes his name with the character "Masa" (正), the NBTHK considers him to have been a smith of the Masatsune line. His surviving tachi shows tightly forged itame with impressive midare-utsuri standing out distinctly, and a chū-suguha with tightened nioiguchi containing ashi and yō -- with the notable observation that "one can perceive a slight Aoe character" in both ji and ha. This is a fine work demonstrating one facet of a style rooted in the earliest Bizen tradition.

The Kanabō group, a lineage whose relationship to the five Yamato traditions "is not clearly established," flourished in Nara (Nanto) in the late Muromachi period. Masatsugu is recognized as the most celebrated smith of this school. Rather than the traditional Yamato-den manner, Kanabō works take the form of Muromachi-period uchigatana with broad mihaba and sakizori, sharing points in common with Sue-Bizen and Sue-Seki styles. Their tempering tends toward large gunome-based midare, with tight nioiguchi into which ashi and yō enter well, and the nioiguchi often takes on a shizumi tendency. Extant naginata are comparatively conspicuous among Kanabō production -- understood as having answered the demands of the warrior monks (sōhei) of Nara's great temples, beginning with Kōfukuji. In katana, the NBTHK describes his best work as displaying "an especially excellent style of workmanship among smiths of the same school."

Suishinshi Masatsugu, also known as Kawabe Hokushi, studied under Taikei Naotane and is said to have become his son-in-law; another view holds that he was the son of the second-generation Masahide (Shirokuma Nyūdō). He used the art-name "Suishinshi," effectively succeeding as the third head of the Kawabe line. His workmanship -- "down even to the style of his chisel-cut characters" -- follows Naotane's manner entirely rather than the broader Suishinshi tradition, and he especially excelled in Sōshū-den and Bizen-den. In the Sōshū mode, his forging shows tightly packed ko-itame with areas of ō-mokume suggestive of Naotane's whirlpool-like uzumaki-hada; the hamon is notare-toned with mixed gunome, chōji, and togariba, with deep nioi, thick nie, and active kinsuji and sunagashi. His Bizen-den works display chōji mixed with gunome and long ashi, with both ji and ha "richly covered in nie" and a bright, clear nioiguchi. He lived and worked in Okachimachi, Shitaya, and died on the eleventh day of the third month of Man'en 1 (1860). The NBTHK describes his finest pieces as works "in which his true strengths are fully displayed."