On a of Eisho 9 (1512), beneath the long signature of Jirozaemon-no-jo Fujiwara Katsumitsu, the smith added a phrase of his own: "as far as my heart can reach, nothing could surpass this" (心の及ぶところ此の上の者あるべからざる也), declaring the blade a work that fully satisfied him. The maker of that boast is the most accomplished bearer of a crowded name. The published sources record that several generations and more than a dozen smiths used the name Katsumitsu among the late- forges collectively called , and that within that crowd the branch titled Jirozaemon-no-jo, the son of Ukyo-no- Katsumitsu, is especially accomplished, counted with Yosozaemon-no-jo Sukesada and Gorozaemon-no-jo Kiyomitsu as a representative smith of the late tradition.
What the published sources name as his individuality is a matter of degree within a shared idiom. Every smith tempers the open-waisted, double-structured , the - that is the diagnostic late- line; Katsumitsu builds his prime on the base, well-packed carrying and fine , over which the temper rides high and bright with and entering richly, the clear and tightening, small interspersed. The distinction the judges draw is that he mixes into that more freely than his fellows, for a more flamboyant effect. "Compared with Sukesada," the sources write, "Katsumitsu shows more conspicuous in the temper, and the so-called crab-claw (kani-no-) irregularities appear relatively less often" (勝光は祐定に比して丁子の刃文が目立ち). On his finest dated the point is put positively: he is "particularly adept at a more splendid workmanship in which abundant are intermingled within the " (乱れの中に丁子を多く交えた一段と華やかな出来を得意としている).
The is the constant beneath that flamboyance. It is the well-packed of late , attaching, finely woven, in places a little standing or flowing; on the best pieces the lies fine as dust ( michin). The classical of old has largely gone from this late steel and appears only faintly on a few blades; one Eisho-2 is read as showing little precisely because the is so strong, so that the itself looks powerful. The answers the , running to a or a pointed tendency, at the tip and a turnback. Across both faces lie the devotional carvings of , a , with , and shrine names such as and Amaterasu Kotaijin, which the sources are careful to call the work of collaborating horimonoshi rather than the smith's own hand.
Katsumitsu is, above all, the great collaborator of the house, and his record is largely one of joint work. With his brother Sakyo-no- Munemitsu he cut the blades long prized as , the two names signed together on katate-uchi and ; on one Eisho-7 the inscription explicitly reads "younger brother, Sakyo-no- Munemitsu" (弟左京進宗光), a line the sources call extremely important material urging a reexamination of the genealogy. The single most celebrated work is the joint with Yosozaemon-no-jo Sukesada, dated Eisho 18, a bold and magnificent with the incised inscriptions Hagun-no- and Sanshin-soku-ittai, commissioned by Ukita Yoshie and called "a masterpiece among " (末備前の薙刀中の傑作である). A of Daiei 3 is a joint work with his son Jirobei-no-jo Harumitsu, and the sources place his working span roughly from the Meio into the Kyoroku era (作刀期間はほぼ明応より享禄に亘っている), late in which, dated Kyoroku 2, he forged a father-and-son joint with another son, Shuri-no-jo Katsumitsu, prized as a record of the collaboration. Beside the flamboyant he tempers a calm, broad and with equal command, the sources observing that the master famed for flamboyant through the -Bijutsuhin Asa-arashi shows, with his uncle's help, an advanced skill even in a straight temper.
What sets Katsumitsu apart within his own school is therefore the reach of his hand rather than a single tell. His bright, -mixed distinguishes his prime from the plainer Sukesada manner, while his command of a clear and his ambition outside the standard idiom mark the upper edge of late- workmanship. The clearest sign of that ambition is a signed Bunki-2 , slender with , that abandons the contemporary for a -based with over a in which a rises; it is read as "a piece conceived with the late- of Kagemitsu and his fellows as its aim" (鎌倉末期の長船景光などをねらいとしたものであろう), an unusually forceful work, though the sources add that its technique does not reach its model. At the far edge a Daiei-6 carries the temper up the into a -like with , more varied than usual. These outliers map the breadth across which the Katsumitsu hand can be known.
Katsumitsu was a productive smith and signed and dated work survives in fair number, yet little of it can ever change hands. Fujishiro grades him Sai-jo . He has no National Treasures; his record runs instead through one Important Cultural Property, the joint with his son Harumitsu held at Nogi Shrine in Tokyo and inscribed Ichigo-ikkoshi, and through the Imperial collection, where signed Bishu Katsumitsu are kept as . The patrimony continues in the houses and old collections grounded in their own provenance, the joint for Ukita Yoshie a treasured heirloom of the Sendai Date family, other blades recording owners such as Uyama Hida-no-kami and Kitamura Yukinao, the Jubi Asa-arashi once held by Matsushita Masatoshi. Beyond these, of the two dozen-odd designated works on record, only a small number sit in the and tiers, so a signed Jirozaemon-no-jo Katsumitsu comes to market only from time to time, and a dated, devotionally carved example, the kind on which the smith once wrote that nothing could surpass it, is a rewarding thing for a collector of late to encounter.