The school arose in Yamashiro Province during the early period, succeeding the old Kyoto traditions -- the so-called kokyō-mono of the and Gojo lineages -- that had been active from the late era onward. The school is celebrated for six brothers: Kunitomo as the eldest, followed by Hisakuni, Kuniyasu, Kunikiyo, Arikuni, and Kunitsuna, "each of whom displayed outstanding technique." Among them, Kunitomo and Kuniyasu were selected as appointed smiths () to the Retired Emperor Go-Toba, and Hisakuni served as an instructor in the sovereign's swordmaking. In subsequent generations the school produced noted masters such as Norikuni, Kuniyoshi, Kunimitsu, and Yoshimitsu. From the early through mid- period the school "rose to prominence and flourished," occupying the central position in Yamashiro swordmaking before yielding that role to the school from the mid-to-late period onward. From antiquity the school's manner has been praised with the canonical expression "the steel's color is bluish and the edge is white," and its works have long been cherished as jōsaku-mono -- productions of superior rank.
The hallmark of work is a of extraordinary refinement. The forging is characteristically a tightly packed , "extremely well-consolidated," upon which fine adheres thickly in minute particles and delicate enter, producing a lustrous (pear-skin) surface texture. A faint -- sometimes described as "a faint, -like effect" -- frequently stands within the . The is founded on or , rendered in , with the consistently described as "bright and clear." Within the tempered area the repeatedly identifies , uchi-noke, , and as characteristic activities, together with fine and . The typically runs straight with a turnback, often showing at the tip. In , school-attributed blades tend toward a slender form with , a pronounced taper from base to tip, and a or -- silhouettes that convey what the describe as "an antique elegance" overflowing with dignity.
Across the designation record, examiners return to a remarkably consistent evaluative vocabulary for work: "the virtues of the school are fully manifested," "bright and clear in both and ," and "a high-class work of dignified character." The meticulously forged is singled out with particular frequency -- "the well-forged, excellent-quality is graceful" -- and the interplay between that refined steel and the calm, luminous is regarded as the source of the school's elevated tone. Even greatly shortened () and unsigned blades are recognized through this nexus of dense , thick , and a enriched by and , features the considers sufficient to affirm attribution to the school as a whole when an individual hand cannot be specified. The tradition is thus positioned as "a foremost representative of Kyō-mono workmanship," embodying the ideal of Yamashiro steelmaking at its most refined -- blades in which the purity of the forging and the brightness of the edge together produce what the examiners consistently characterize as a sense of "lofty dignity" and "high rank."