The published sources open Kunitoshi's record with a single settled fact: he was "the first smith of the line to crown his name with the character , and all who followed took the practice from him". Traditionally the son of Kuniyuki, he worked in Kyoto at the close of the period. Dated blades open in the Shoo and Einin eras, fall silent for a time, then resume in Showa and continue through Bunpo, Gen'o and Genko. A National Treasure of the Tokugawa Reimeikai, signed Magotaro and dated Shoo 5 (1292), belongs to the first of these eras; the published sources record that Magotaro is generally held to be Kunitoshi, that this is the only blade signed in that form, and that its stately shape and calm Kyoto allow the received view to stand. A of Showa 4 (1315) in the Tokugawa Art Museum bears the age inscription seventy-five (七十五歳), and a work of Genko 1 (1321), cut at eighty-two, stands near the end of his production. This run of dated pieces is the backbone of the late chronology.
His hand is the mainline at its most refined. The are slender or of standard width with a pronounced taper, the curvature -zori, turning to a rounded wa-zori on shortened blades, and the point small or medium. On this body he burns a or in with and mixed in; and enter well, at times slanting toward the in the Kyoto manner the published sources call -. appears in places, fine and run through the , and the is tight and bright; the turns in a calm , the tip lightly swept. The judgment the published sources attach to the whole is consistent: "a refined and calm manner that is Kyoto work through and through".
The carries as much of the attribution as the : a tightly knit with thick, often dust-fine , fine , and a standing clearly over it; one appraisal adds that "the refinement of the in particular deserves special mention". Here and there the larger, softer patches the texts call - (来肌) intrude, and on the may flow toward in places, both accepted as marks of the school rather than flaws. The packed , the fine over it and the standing are what the appraisals return to whenever an unsigned blade is settled on his name.
Nearly half of his published record is : the sources state again and again that where the two-character Kunitoshi left a single example, the Aizen Kunitoshi, Kunitoshi left many. These are and , of standard width or slightly elongated, with the quiet uchi-zori of the late period; the may take a shallow , the of the often runs down long, and the is frequently hardened in. Carving is habitual, a with a slender or set beside it, or over , the added side groove being a practice "peculiar to work". Honma's inventory sums up the balance of his output: and are both plentiful, and he is a master of whom one cannot say whether the or the is his greater strength. rules him, yet a small group stands at the opposite limit. Its representative is a National Treasure , and a raised at the 27th session, slender, high in -zori, mixing large-lobed with the thick in the , is called "the most flamboyant range of work in his oeuvre", "just evoking Niji Kunitoshi". That evocation is the heart of the school's classic question, whether the two-character Kunitoshi and the three-character Kunitoshi are one smith or two. The combined dated works run from Koan 1 (1278) to Genko 1 (1321), some forty years and no strain for a single career, and counted back from the age inscription of seventy-five, the lone dated Niji blade falls at age thirty-eight. In recent years, the sources write, re-examination of the workmanship and the signature forms has brought the same-smith view toward acceptance, prompting a rethink of the two-smith position, and the blades above are read as key material on his side of the divide. The signatures hold further scholarship: the Gen'o pieces turn cursive enough that the notes weigh his old age against a second generation; rare works add the Minamoto surname, and Honma's inventory of the Imperial collection, recording a signed Minamoto Kunitoshi and dated Gen'o 3, proposes as a question for further study that the Minamoto works may be by a different smith of the same name, their workmanship otherwise no different; and on a Genko 2 folded-signature once worn by Shimazu Narinobu, the character is cut in the manner of his pupil Kunitsugu, read as one of the rare cases of the pupil signing in the master's name, the third such example known.
The contrast with Niji Kunitoshi is the standing formula of his appraisals: against a grand body with point and a flamboyant -dominated , the three-character works set a slender or standard build, a or with small-patterned , and a gentle effect overall, so the two hands can be told apart even while the one-smith question stays open. His other neighbors lie within the school. His calmest, largest are read first toward Kunimitsu before the dignity of the work, "a grade higher", settles the attribution on Kunitoshi. His pupils Kunimitsu and Kunitsugu carried the school through the end of , and the line between master and pupils is fine enough that the Yuki Kunitoshi, a recorded in the , is itself said at first sight to suggest Kunimitsu and Kunitsugu.
For a master of this rank he is unusually approachable. Fujishiro grades him Sai-jo ; five of his blades are National Treasures and eight more are Important Cultural Properties, with twenty-one and one hundred thirty-seven beneath them, one hundred fifty-eight blades across those two tiers. Signed work is abundant, one hundred thirty-two signed against forty-nine unsigned here, which is why his chronology can be written at all. Those thirteen blades are held as patrimony and will never trade, among them the Magotaro , the of Futarasan Shrine at Nikko and the of Atsuta Jingu dated Showa 5 (1316); the Tokugawa Art Museum holds the age-75 , and other works rest with the Tokyo National Museum, the Nezu Museum, the Sano Art Museum and the Kurokawa Institute. Forty-six blades carry recorded provenance: Toyotomi Hideyoshi, the shogun Tokugawa Iemitsu, the Owari and Kishu Tokugawa, the Maeda, the Uesugi, the Shimazu of Kagoshima and the Sanada of Matsushiro. Yet thirty-two works are recorded in private hands and many more sit in the tradeable tiers, so a or by Kunitoshi, late Yamashiro work in its purest form, remains a goal a serious collector can actually reach; the blades and the dated pieces stand effectively beyond the market.