Hiromasa is the mid- smith whose few signed and dated blades fix one of the most divided names in late work. Three of his four designated swords carry a date, the of Hotoku 2 in 1450 and Kosho 2 in 1456 and the of Bunan 5 in 1448, all cut -ju Hiromasa on an unshortened tang, and it is on these dated pieces that the whole line turns. The published sources are explicit about the difficulty, observing that the Hiromasa name was borne by several generations active continuously from the period through the , each a capable hand, yet that signed examples bearing a date are exceedingly few. Their own words on one of the dated run 「広正は同名が何代かあって、南北朝期から室町時代に及んで活躍しており、それぞれに上手であるが、現存する有銘且つ年紀のあるものは極めて少い」, a name worked by several hands across two centuries of which the dated survivors are the rarest. This maker is transmitted as the third-generation Hiromasa of , and he belongs to Sue-, the late line that carried the - of Masamune and his successors Hiromitsu and Akihiro down through the period.
His characteristic hand is the that builds into . Over the temper he scatters above the , and on three of the four blades these detached spots gather with and until the tempering spreads across the whole blade as the all-over that the late school made its own. The stays tight and adhere well, and enter the temper, and runs through it repeatedly, with and a -like temper mixed with on the latest . This is the - read in its register, where the restrained and of the founders has given way to a more demonstrative all-over manner. On the quietest of the four, the Bunan , the gathers only near the rather than flooding the blade, so the hand can be watched stepping back from full toward a small with .
The is the standing steel from which that temper rises. He forges sometimes a tight and sometimes an that stands and opens into , at one point mixing ohada, and adheres across it. The construction is the middle bearing of , a or of standard width with and a , at times grown and deep in , while the is a broad grown with high . The answers the disturbed temper, turning in on most of the blades, standing with a long turnback on others, and on the Kosho brushed in to a pointed return. Across both faces he cuts conspicuous , and a grass-style , and within a or he sets a or paired rods in raised relief, the carving fine and the relief well-raised. The published sources count this carving among the distinctive merits of every one of these blades; of the Hotoku they write 「地刃に時代の様相と相州物の伝統的な作風を見せ、彫物もまた特色あるもので見事である」.
Because the generations cannot be told apart with certainty, the dated and -signed pieces do double duty as workmanship and as documents. The undated of the 25th session is judged to date to around the Hotoku era on the evidence of the others, the published sources stating plainly of the name 「年紀作は稀であり、各代の区別は明確にし難い」, that dated works are rare and the several generations difficult to separate. So the record proceeds by anchoring the rest of the line to the few inscriptions that survive, and the Bunan adds an instructive accident: its date inscription was reduced to a soko-mei on the tang reverse when a was carved in later, legible but, in the words of the published commentary, regrettable, a detail that itself records the carving habit of the line. The hand is read as one manner across these four, not as separate styles, the variation between full and a quieter temper being the range of a single workmanship rather than the mark of distinct masters.
Within the succession Hiromasa stands at a working centre rather than at a founding edge, the school whose technical identity is bold over a standing with accomplished carving. His own -free, -laden and his pointed, disturbed set him within that idiom rather than against any rival, and the published sources read each of his blades as the period itself made visible, calling the Kosho 「この時代の相州物の典型的且つ代表作の一口」, a typical and representative example of work of its time. The line he carries is bound forward into the principal Odawara- succession, for the school commentary transmits that the first-generation Tsunahiro, active in the Tenbun era, was a descendant of Hiromasa, summoned by Hojo Ujitsuna to Odawara and granted the character to change his name, a lineage reaching into the period. His mid- hand, with its and its devotional carving, stands among the foundational manners that the later Odawara smiths, Tsunahiro and Tsunaie among them, carried to the end of the feudal age.
Hiromasa is known through a small and uniformly signed designated record of four blades, the of the 17th session, two of the 18th, and the of the 25th, every one and cut -ju Hiromasa, three of them dated. His skill is rated Jo in the Fujishiro ranking, and the published commentary calls his work splendid, the workmanship of the dated excellent and the carvings distinctive. There are no National Treasures and no Important Cultural Properties among his blades, and no provenance is recorded for any of them, so the honest measure of his standing is the rarity itself, the few and dated survivors of a name that several generations worked across two centuries. For a private collector his swords are encountered only seldom, all four at the level, none locked away as national patrimony but none coming to market with any frequency either; a signed and dated Hiromasa, of the kind the published sources hold up as the documentary anchor of the whole divided name, is among the less common things a student of late work is likely to meet, and a quiet reward when one does, for in it the register of the - can be read whole.