Yukimitsu worked in Sagami at the close of the Kamakura period, a pupil of Shintogo Kunimitsu and a brother-student of Masamune and Norishige, and he is read by the published sources as slightly the senior of the three. With those two he carried his teacher's new Soshu tradition forward and brought it to completion[[c:1]]. The surviving signed work is limited to tanto cut with the two-character mei 行光[[c:2]], so the smith is known above all through o-suriage mumei attributions, and the great houses kept his blades for that reason.
The foundation is a Soshu jigane of unusual quality. The forging is an itame, often mixed with mokume and with passages of nagare-hada, tightly worked yet with the grain standing in places; over it the ji-nie lies thick and fine, and abundant chikei (地景) enter, the steel clear and lit. This bold itame laced with thick chikei is the constant beneath every manner he works, and the old texts say as much when they speak of the breadth of his range[[c:3]]. Whatever the temper above it, the published sources return to one point that holds across all of his work: the ji and ha are richly charged with nie, with chikei, kinsuji and yubashiri conspicuously active, displaying the marvel of nie[[c:4]].
His quieter and more frequent manner descends directly from Shintogo. Over the chikei-laced jigane runs a suguha, or a suguha tending to shallow notare, mixed with ko-gunome and small ashi and yo, the nioiguchi somewhat deep and thickly covered in nie, with hotsure and drifting yubashiri at the habuchi and fine kinsuji and sunagashi within. The judges read these mumei attributions as the gentle, small-patterned side of him, noting that the unsigned attributed pieces are mostly a calm suguha or a shallow quiet midare and that the jigane is on the whole in the Shintogo manner[[c:5]]. This is the register that connects him most plainly to his teacher.
His bolder manner is the one the older profiles understated, and the boshi is where it shows. Far from a plain ko-maru that simply turns back, the temper of the point most often sweeps out strongly in hakikake (掃きかけ): the published sources record it as midare-komi with vigorous brushing that builds into a flame shape[[c:6]], the point at times pointed or burned through in yakizume, and on the calmer pieces as a straight run into a small round that still brushes out[[c:7]]. Beneath that point the temper opens into a notare-based midare with gunome and ko-gunome, sometimes a large-patterned midare reaching toward hitatsura, the kinsuji and sunagashi running busily and the nioiguchi deep and bright. The corrected reading of the boshi, ko-maru carrying conspicuous hakikake into a midare-komi and at times a pointed return, belongs with the thick chikei as a recognition key for him.
For the connoisseur the two manners share the same core, and that core is what carries an attribution when the mei is gone. The thick dark chikei, the deep bright nioiguchi of the upper Soshu hands, the busy kinsuji and sunagashi, and the swept hakikake boshi recur whether the temper above is a calm suguha or an open midare. The breadth of range is itself part of the fingerprint: where Masamune and Sadamune run hotter and larger in pattern, Yukimitsu keeps the quieter, smaller-patterned hand, and the judges place him toward Shintogo and Norishige and explicitly apart from Masamune and Sadamune. On one Tokubetsu-Juyo tanto they rate the make a notch finer than Sadamune's reach, while across his range the temper stays the more restrained. Fujishiro grades him Sai-jo saku, and among all swordsmiths his Tokubetsu-Juyo total stands near the very top.
Acquirability follows from the rarity. Of the works on record the overwhelming majority sit in the Tokuju and Juyo tiers, with a small number locked away forever as National Treasure and Important Cultural Property and never tradeable, and a single Kokuho among them. The recorded holdings read as a roster of the great collections and shrines: the Tokugawa Museum and the Uesugi Jinja, the Tokyo National Museum and the Kyushu National Museum, the Kurokawa Research Institute, the Seikado Bunko Art Museum, the Tokyo Fuji Museum, the Kunozan and Nikko Toshogu among them. The provenance chains carry the same weight, the named blades having passed through Tokugawa Ieyasu and Toyotomi Hideyoshi, the Hosokawa, the Uesugi and the Date houses, with the Meibutsu Oshima Yukimitsu among the famous wakizashi. A blade by this smith is for practical purposes unattainable on the open market, and the rare piece that does surface trades at the very top of the field.
