Muramasa is the founder of the Sengo line of Ise Kuwana and the smith who set the manner that bears his name, and the published sources fix him firmly to a single point in time. The oldest extant date in the whole line is Bunki 1 (1501), carried by the dated katana signed "Seshu Kuwana-ju Uemon-no-jo Fujiwara Muramasa saku" preserved as a Juyo blade of the 40th session; with the full signature giving the residence, the personal name Uemon-no-jo and the smith name, the published commentary calls it "of high documentary value for research on Muramasa"[[c:1]]. From that fixed point the prevailing scheme reads the Bunki pieces as the first generation, the Tenbun as the second, the Tensho as the third. Against this dated record the institution sets aside the famous legend: Muramasa, it writes, "was popularly transmitted as a pupil of Masamune, but this is unfounded"[[c:2]], a smith whose line begins instead "near the close of the Muromachi period"[[c:3]]. His manner shares common features with Mino, Shimada and Sue-Soshu, and resembles Heianjo Nagayoshi above all, so closely that the sources raise the view the two stood in a teacher-pupil relation: "it is especially close to that of Heianjo Nagayoshi"[[c:4]].

The feature the published commentary names again and again as his own is the symmetry of his temper. "The characteristic of his manner," one description states, "is that the hamon on omote and ura match, and the valleys of the midare press in toward the edge"[[c:5]]. The mirror-image alignment of front and back is the Muramasa hallmark, and the sources return to it on blade after blade: a wakizashi is called typical because "the hatori on both front and back is precisely matched, clearly demonstrating a characteristic feature of Muramasa." Over a body usually wide, often short with deep sori and sakizori, or a hira-zukuri sun-nobi wakizashi, he fires a notare-based midare mixed with gunome and large gunome, ashi entering, the nioiguchi deep and thick ko-nie adhering, with kinsuji and sunagashi along the edge. Box-shaped elements appear among the midare, and the valleys drive down sharply toward the ha. The boshi runs straight to a small round point or enters the midare and sweeps; on the bolder pieces the temper carries down into muneyaki.

The forging is itame that tightens then stands somewhat, with flowing grain mixed in and ji-nie; the published sources call it itame tending toward hada-dachi, frequent among works of the Sengo line, sometimes a masame tendency, the steel at times slightly blackish with a shirake cast. On the finest pieces the jigane is well refined and the nioiguchi bright, the ji-nie thick and chikei abundant. His general run of work, by contrast, is described more plainly, the nioiguchi "tight and subdued, with mura-nie commonly forming" (匂口は締りごころで沈み, 叢沸のつくのが一般である). What he is not is a hitatsura smith. Even his most flamboyant wakizashi, with conspicuous muneyaki, is described only as "presenting an appearance akin to hitatsura" rather than the full tobiyaki-strewn fields of the Nanbokucho Soshu hands; the muneyaki and the boxed midare are his, but the all-over temper is not, and this absence is itself a tell that separates him from the Hiromitsu-Akihiro manner the legend invoked.

The founder's hand divides between two registers of signature and one devotional group. The full long signature, "Seshu Kuwana-ju Uemon-no-jo Fujiwara Muramasa saku," carries the dated Bunki blades and is read as the first generation; the bare two-character "Muramasa" is undated, its generation read from the chiselling and workmanship. On the dated Bunki 1 katana the temper is a notare with gunome worked in a nioi-dominant manner, carrying a tendency toward nijuba, which the published sources say differs somewhat in feeling from the work attributed to the second generation. Distinct from these is a group marked by Nichiren devotion. On the Juyo Bijutsuhin katana dated Eisho 10 (1513) the temper forms hakomidare low in the blade and runs up to suguha, omote and ura matched, with the Lotus Sutra title Myoho-renge-kyo cut on the blade itself; another wakizashi carries bonji with lotus, ken and an incised Hachiman Daibosatsu in superimposed relief. The generational boundary in these later-dated pieces is not yet firmly settled: the published commentary repeatedly notes that the divisions among the generations have not yet been firmly established, so the Eisho and Tenbun assignments are read with caution.

Where he stands among his neighbours the sources draw by his own traits rather than by borrowed comparison. His manner shares common features with Mino, Shimada and Sue-Soshu; it is nearest Heianjo Nagayoshi; and the matched temper with the down-pressing midare valleys is the thread that runs through the whole line and marks it off. His boldest work reaches higher still. On the Tokubetsu Juyo katana of the 16th session the temper is exceptionally wide, notare with large gunome, the nioi extremely deep and thick ko-nie adhering, the boshi deeply tempered to an ichimai appearance, and the judges read its model as the old master Go: it "may be thought to have taken as its model the manner of the old Go"[[c:6]]. They call it a masterpiece of the first generation, one that "in this work in particular gives the impression of surpassing even the second generation"[[c:7]]. The line continued under the same name through the second generation of the Tenbun years, held the most skilled and most prolific, and the third of the Tensho years, and from the school issued the pupils Masashige and Masazane. Its end was political rather than artistic: by the early modern period the name "came to be shunned by the Tokugawa house, and so the name could no longer be carried on"[[c:8]].

Muramasa is Sai-jo saku in Fujishiro's grading and rates 800 in the Toko Taikan, the representative swordsmith of late-Muromachi Ise. His Nichiren faith is read straight off the iron: because there are blades on which he "cut the title Namu-Myoho-renge-kyo"[[c:9]] he is taken for a believer of the sect, and the published commentary ties this to the region, noting that "in the Ise district of that time devotion to the sect was by no means uncommon"[[c:10]]. The unsigned Juyo katana of the 12th session, whose Muramasa signature was shaved away, is read by the published commentary as the work of a Nichiren believer forged for one such cleric. On record stand fourteen blades across the Tokubetsu Juyo and Juyo tiers, one Tokubetsu Juyo and thirteen Juyo, together with the Juyo Bijutsuhin Lotus Sutra katana; that blade bears "Nabenobu" in silver inlay on the nakago mune and is held to have been owned by Nabeshima Shinano-no-kami Katsushige, recorded at certification in the Nabeshima house. A first-generation wakizashi survives "transmitted as a personal possession of Oda Nobunaga"[[c:11]], its aikuchi mounting bearing the Oda mokko crest in maki-e. None of the founder's blades carries the highest patrimonial designations, so none is locked permanently out of private hands; what survives sits almost wholly in the Tokubetsu Juyo and Juyo tiers, held more often than traded. A first-generation Muramasa of secure date and matched temper is a landmark when it appears, and it appears only from time to time.

Muramasa is the founder of the Sengo line of Ise Kuwana and the smith who set the manner that bears his name, and the published sources fix him firmly to a single point in time. The oldest extant date in the whole line is Bunki 1 (1501), carried by the dated katana signed "Seshu Kuwana-ju Uemon-no-jo Fujiwara Muramasa saku" preserved as a Juyo blade of the 40th session; with the full signature giving the residence, the personal name Uemon-no-jo and the smith name, the published commentary calls it "of high documentary value for research on Muramasa"[[c:1]]. From that fixed point the prevailing scheme reads the Bunki pieces as the first generation, the Tenbun as the second, the Tensho as the third. Against this dated record the institution sets aside the famous legend: Muramasa, it writes, "was popularly transmitted as a pupil of Masamune, but this is unfounded"[[c:2]], a smith whose line begins instead "near the close of the Muromachi period"[[c:3]]. His manner shares common features with Mino, Shimada and Sue-Soshu, and resembles Heianjo Nagayoshi above all, so closely that the sources raise the view the two stood in a teacher-pupil relation: "it is especially close to that of Heianjo Nagayoshi"[[c:4]].

The feature the published commentary names again and again as his own is the symmetry of his temper. "The characteristic of his manner," one description states, "is that the hamon on omote and ura match, and the valleys of the midare press in toward the edge"[[c:5]]. The mirror-image alignment of front and back is the Muramasa hallmark, and the sources return to it on blade after blade: a wakizashi is called typical because "the hatori on both front and back is precisely matched, clearly demonstrating a characteristic feature of Muramasa." Over a body usually wide, often short with deep sori and sakizori, or a hira-zukuri sun-nobi wakizashi, he fires a notare-based midare mixed with gunome and large gunome, ashi entering, the nioiguchi deep and thick ko-nie adhering, with kinsuji and sunagashi along the edge. Box-shaped elements appear among the midare, and the valleys drive down sharply toward the ha. The boshi runs straight to a small round point or enters the midare and sweeps; on the bolder pieces the temper carries down into muneyaki.

The forging is itame that tightens then stands somewhat, with flowing grain mixed in and ji-nie; the published sources call it itame tending toward hada-dachi, frequent among works of the Sengo line, sometimes a masame tendency, the steel at times slightly blackish with a shirake cast. On the finest pieces the jigane is well refined and the nioiguchi bright, the ji-nie thick and chikei abundant. His general run of work, by contrast, is described more plainly, the nioiguchi "tight and subdued, with mura-nie commonly forming" (匂口は締りごころで沈み, 叢沸のつくのが一般である). What he is not is a hitatsura smith. Even his most flamboyant wakizashi, with conspicuous muneyaki, is described only as "presenting an appearance akin to hitatsura" rather than the full tobiyaki-strewn fields of the Nanbokucho Soshu hands; the muneyaki and the boxed midare are his, but the all-over temper is not, and this absence is itself a tell that separates him from the Hiromitsu-Akihiro manner the legend invoked.

The founder's hand divides between two registers of signature and one devotional group. The full long signature, "Seshu Kuwana-ju Uemon-no-jo Fujiwara Muramasa saku," carries the dated Bunki blades and is read as the first generation; the bare two-character "Muramasa" is undated, its generation read from the chiselling and workmanship. On the dated Bunki 1 katana the temper is a notare with gunome worked in a nioi-dominant manner, carrying a tendency toward nijuba, which the published sources say differs somewhat in feeling from the work attributed to the second generation. Distinct from these is a group marked by Nichiren devotion. On the Juyo Bijutsuhin katana dated Eisho 10 (1513) the temper forms hakomidare low in the blade and runs up to suguha, omote and ura matched, with the Lotus Sutra title Myoho-renge-kyo cut on the blade itself; another wakizashi carries bonji with lotus, ken and an incised Hachiman Daibosatsu in superimposed relief. The generational boundary in these later-dated pieces is not yet firmly settled: the published commentary repeatedly notes that the divisions among the generations have not yet been firmly established, so the Eisho and Tenbun assignments are read with caution.

Where he stands among his neighbours the sources draw by his own traits rather than by borrowed comparison. His manner shares common features with Mino, Shimada and Sue-Soshu; it is nearest Heianjo Nagayoshi; and the matched temper with the down-pressing midare valleys is the thread that runs through the whole line and marks it off. His boldest work reaches higher still. On the Tokubetsu Juyo katana of the 16th session the temper is exceptionally wide, notare with large gunome, the nioi extremely deep and thick ko-nie adhering, the boshi deeply tempered to an ichimai appearance, and the judges read its model as the old master Go: it "may be thought to have taken as its model the manner of the old Go"[[c:6]]. They call it a masterpiece of the first generation, one that "in this work in particular gives the impression of surpassing even the second generation"[[c:7]]. The line continued under the same name through the second generation of the Tenbun years, held the most skilled and most prolific, and the third of the Tensho years, and from the school issued the pupils Masashige and Masazane. Its end was political rather than artistic: by the early modern period the name "came to be shunned by the Tokugawa house, and so the name could no longer be carried on"[[c:8]].

Muramasa is Sai-jo saku in Fujishiro's grading and rates 800 in the Toko Taikan, the representative swordsmith of late-Muromachi Ise. His Nichiren faith is read straight off the iron: because there are blades on which he "cut the title Namu-Myoho-renge-kyo"[[c:9]] he is taken for a believer of the sect, and the published commentary ties this to the region, noting that "in the Ise district of that time devotion to the sect was by no means uncommon"[[c:10]]. The unsigned Juyo katana of the 12th session, whose Muramasa signature was shaved away, is read by the published commentary as the work of a Nichiren believer forged for one such cleric. On record stand fourteen blades across the Tokubetsu Juyo and Juyo tiers, one Tokubetsu Juyo and thirteen Juyo, together with the Juyo Bijutsuhin Lotus Sutra katana; that blade bears "Nabenobu" in silver inlay on the nakago mune and is held to have been owned by Nabeshima Shinano-no-kami Katsushige, recorded at certification in the Nabeshima house. A first-generation wakizashi survives "transmitted as a personal possession of Oda Nobunaga"[[c:11]], its aikuchi mounting bearing the Oda mokko crest in maki-e. None of the founder's blades carries the highest patrimonial designations, so none is locked permanently out of private hands; what survives sits almost wholly in the Tokubetsu Juyo and Juyo tiers, held more often than traded. A first-generation Muramasa of secure date and matched temper is a landmark when it appears, and it appears only from time to time.