Sadayuki belonged to the school of Province, a lineage that emerged in the early period and broke decisively from the classical styles previously characteristic of Kyushu workmanship. Traditionally regarded as a student of Yukihiro, with an alternative transmission placing him under Yasuyoshi, Sadayuki is recorded with an extant date of Shohei 12 (1357) in the , placing his activity squarely at the zenith of the period. One theory holds that he later relocated to Aki Province. Signed works are few, and the overwhelming majority of attributions rely on appraisals, including examples authenticated by Koshitsu.
The designated pieces exhibit the unmistakable technical vocabulary of the lineage in both and . The forging shows mixed with and , with fine , thickly applied , and abundant , producing a bright and luminous . The is characteristically founded on a shallow mixed with , , and , with strongly adhering and frequent including , , and intermittent at the . The enters and turns back with a pointed tendency, often showing . Where the is particularly thick, appears along the , lending the temper a vigorous and expressive character.
Sadayuki's works preserve the heroic proportions of their era: wide , extended , and generous in the long blades, and forms in the shorter pieces. Both and are consistently bright and clear, confirming the school's refined sensibility, and the sound condition of these blades attests to the enduring quality of Sadayuki's forge craft.
