The oldest Yukiyasu, the published sources record, is the preserved at Sanage Shrine, an Important Cultural Property, and after it comes the called Sasanuki, handed down in the Kabayama family, a branch of the Shimazu house. Yukiyasu is the head name of the Naminohira school of Satsuma. Its founder by tradition is a smith named Masakuni, said to have come from Yamato to Naminohira in Taniyama District in the late period, though no securely attributable work of his survives. His son was Yukiyasu, and the name passed down the main line generation after generation into the era. The published sources call the smiths and works no later than the period Ko-Naminohira, and one entry places Yukiyasu in the stream of the Yamato Senjuin school, a descent it finds borne out by the style of the work.
His manner is close to Yamato, and the published sources name the points that make it Naminohira. The flows and turns to a strong toward the edge, and the steel carries a viscous, soft feeling the sources call . Over it runs a narrow , finely frayed with and worked in , with and , the clouding in places to . At the base the temper drops away in a . Of the classical signed raised to the sources write that the steel is "viscous, with " and that the temper is "dropped greatly at the base", and they read the soft steel, the clouded and the dropped base as the points of the school.
The is the steadiest of these marks. Fine lies thick on the early , enter, and on another signed the sources note that the steel "has a feeling". A whitish rises on several blades, and on the later broad works the steel stands a little and turns somewhat dark. The runs straight to a , or turns in a small round on one face. Activity in the edge varies with the blade. One early , compared with ordinary Ko-Naminohira, shows less and fine and working well, while a signed of the period is called "restrained and deeply flavoured in manner".
His record divides into two forms of the one hand. The first is the slender, classical early- , and signed, with a small , a high and wide , deep and , its four-character signature cut with a thick chisel on the upper . The second is the broad, powerful work of the late to early period, long and wide with a high . Its finest example is a that first passed and then , its carrying faint streak-like from base to tip. Beside these stand a fully preserved , which the sources value as one of the school's few surviving examples, and a shortened signed on the with the added character zo, a rarity they call valuable as documentary material. Across the span the sources are frank about dating: "as a rule the manner does not change with the age, and this is the point of recognition for this smith and his school".
The published sources set his traits within a wider Kyushu picture rather than claim them for him alone. The fine , the steel, the weak and clouded and the at the give the school an antique fragrance, and the entry notes that this is "shared with the works of other classical Kyushu schools such as Yukihira and Miike Mitsuyo". Against Yamato proper he is told by that soft steel and the dropped base. The broad they judge "without flamboyance, yet a savour-rich masterpiece attributed to this smith, showing a dignified presence", and they hold it the Yukiyasu that represents the school.
For the collector Yukiyasu is a rare early Kyushu name, graded Jo-jo by Fujishiro. He has no National Treasures. His record runs through one Important Cultural Property, one prewar , and seven blades in the and tiers, two of which rose to : the classical signed and the broad . Of recorded whereabouts, a is held at Sanage Shrine, and the Sasanuki of the Kabayama family ties the name to its home province. The published sources stress that Ko-Naminohira Yukiyasu are few and dated examples rare, so a signed piece comes to light only seldom, and a privately held example with the soft steel and dropped base is a notable thing for a collector to encounter.