The blades gathered here belong to the classical line of province seated at Hakata, whose smiths the consistently place within what they call the Kyūshū classical group (Kyūshū koten-). The sampled works carry the signatures and attributions of three men of one descent: Ryōsai (良西), named in the as founder of the line; Sairen (西蓮), the tonsured name of Kuniyoshi, recorded as Ryōsai's son; and Jitsua (実阿), given as Sairen's son. The date the group to the late period, with Jitsua's signed and dated pieces (Genkō 3, 1335 Kenmu 2) carrying the work into the early . Several entries connect Sairen to the Hakata Dangi-sho, the Chinzei administrative office set up against the Mongol threat, citing Kōzan for a signed " no , Hakata Dangi-sho, Kuniyoshi Hōshi Sairen, Bunpō 1." The also gesture beyond the three: Nyūsai (Nyūsa), recorded as Ryōsai's younger brother or pupil, and , named as Jitsua's son who would carry the house toward and a matured Sōshū-den.
Across the blades sampled, one forging idiom recurs. The is on a large scale, the grain standing () and flowing, tending to toward the edge, mixed in places with and ; adheres with fine , and the steel carries a dark "kana-iron" cast, often with a faint whitish or . The is built on , low in height, fraying into along the , with the drawn toward , a moist and slightly blurred quality; , uchi-noke, , and enter, sometimes with and sanjūba effects, and or interspersed. run straight into a return, frequently with . Within this shared vocabulary the mark divisions. Ryōsai is known from a single reliable , a piece with conspicuous , a subdued () , and a dropped temper at the (-otoshi). Jitsua is read as the coarsest and most vigorous hand of the line, his forging the boldest in pattern and the one most apt to show an -like texture, a trait the use to separate his work from Sairen's quieter .
For the lean on this conjunction of dark, standing and a fraying with , treating the entwined with the forging as the signal that distinguishes the hand from other traditions; the hint and rough patterning push an attribution toward Jitsua specifically. The named works carry weight beyond style. A bears the gold-inlaid appraisal of Kōtoku, and other blades hold by Kōtsune valuing a Sairen at 150 . Provenance recorded in the reaches the highest houses: a Sairen transmitted in the Tokugawa shogunal house, another in the Shigetomi Shimazu family, and a Jitsua of unusually bold kept in the Uesugi family. The Jūyō-Bijutsuhin entries add early-certified and signed Dangi-sho Kuniyoshi, Sairen, and Jitsua, with a Jitsua dated Kenmu 2. Read together, the blades present not as a single voice but as a short, traceable descent whose archaic Kyūshū , dark steel, and fraying edge form a recognizable register, and from whose later reach the Sōshū-den of is said to have grown.