Seki in province supplied the base for the Kanesada line, whose blades the places among the representative work of the - in the closing phase of the period. The consistently pair Kanesada with Kanemoto as the two leading masters of , the late Seki group active with Seki as its center, where (as one 31st-session notes) the smiths flourished second only to . Within the line the signatures sort by how the character (定) is cut: when the element under the (う冠) appears as 之, the smith is called (之定), and when it appears as 疋, Hikisada (疋定). Several generations and individuals carried each name, which the Imperial-collection ( #85 to #87) state makes precise identification difficult; a kanwaku of ordinary workmanship is mentioned alongside them, and one entry records that a Kanesada was called Hachiya Seki, residing at Hachiya in the province. The standout is the second-generation Izumi no Kami Kanesada, the the records single out for high technical ability and for receiving, rare in the era, the court title Izumi no Kami. Per the Shūroku cited in the 14th Tokuju , he first cut in (standard script) and shifted to the 之 form, the change placed by extant works between the eleventh month of Meiō 8 and before the eighth month of Meiō 9, with signatures running on to about Daiei 6 (1526). Several blades carry domain provenance: works pass through the Tosa Yamanouchi, Akita Satake, Shimazu, and Tatebayashi Akimoto families, and one was made for Takeda Nobutora, father of Shingen.
The shared vocabulary the draw is a refined , frequently mixed with (flowing grain) or and tending to stand up as , carrying , , and very often a whitish . Against Kanemoto's pointed, -dominant , Kanesada is defined by variety: rounded , , and gunome-chōji, with and -like elements mixed in, and entering, and running, and a the records repeatedly call bright and clear (). A second register is the elegant the name -, an evocation of work that the 30th-session likens directly to Kuniyoshi; the 45th-session ties the Kyō-modeled to a early signature. The hand is read most clearly in : a gunome-chōji base broken into modest rises and falls, a that is brighter and more thoroughly nerareta (well-kneaded) than ordinary , and, on , a slender to standard with pronounced taper and slightly elevated . When turns to the silhouette broadens with a larger . The runs to , at times Jizō-flavored, and a -like stand-up at the recurs. Lesser Kanesada and the Hikisada works read as plainer and, where -heavy dominates a , the Imperial entries judge the manner unusual and late.
For the registers converge on Seki signatures: taka-no- (and on often ) , or, in later years, tangs with file, and the diagnostic 之-versus-疋 reading of . Tang-form drift, giving way to , lets the 50th-session be dated to late Daiei. The cutting reputation is carried in metal: cutting-test inscriptions appear on the 14th-session Tokuju , owned as a personal sash-sword by Miura Shōgen, karō of the Tokugawa, and on a 58th-session , while another names Kosuga Tatewaki of the Tsuyama Matsudaira and another the Nawa cutting record. The Jūyō-Bijutsuhin for Takeda Nobutora is recorded in the Kokon Kaji Bikō and -tō Taikan; the 62nd-session survives in the of Kōzu Haku. On this evidence the line holds standing as the tradition's most accomplished late voice, its peak hand for a brightness and refinement uncommon for Seki.