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The Sa school
According to the 往昔抄 (Ōjakushō), as summarised by the Japanese Wikipedia, the Chikuzen school runs from 良西 (Ryōsai), in the middle of the Kamakura period, to 西蓮 (Sairen), 実阿 (Jitsua), Sa, called Ō-Sa, and Sa Yasuyoshi. Ō-Sa signs with a single character, 左 (Sa), and is counted among the ten pupils of Masamune.
The NBTHK Sword Journal (no. 734, March 2018) gives Ō-Sa tantō dated 1338, 1339 and 1340, and places between 1340 and 1350 the school’s move to the full Sōshū style.
Sadayuki is one of the 末左 (Sue-Sa), the swordsmiths of the school of the following generation.
From Chikuzen to Aki
The Osaru website makes him a pupil of Samonji, says that he moved from Chikuzen to Aki, today’s Hiroshima, where he gave rise to the Geishū-Sa branch, and gives him some 650 years of age, around the Shōhei era (1346–1370). A ranking of kotō quality of unidentified origin also places him in Shōhei and in Aki, among the 上々作 (jōjō-saku).
His son
The corrected keizu of the school, the 校正 (Kōsei), and the Osaru website make him the father of Sa Kunihiro. Other genealogies make Kunihiro the son of Yasuyoshi or of Yoshihiro, and Kunihiro’s Jūyō paper writes it 貞行 (Sadayuki), with a different first character.
His work
No blade identified under his name has been found, either signed or attributed, and there is no description of his steel, his temper, his point or his signature. All that is known is that he belongs to the Sa school, of wide blades, thin kasane, shallow sori and ō-kissaki, according to Markus Sesko.
The Osaru website marks him as 良業物 (yoki-wazamono), the third of the four cutting categories of the treatise 懐宝剣尺 (Kaihō Kenjaku), of 1797. The wazamono list of the Japanese Wikipedia does not include him in the extracts reviewed: it remains to be checked against the text of the treatise.
He does not appear in the Kyōhō meibutsuchō, nor in the lists of the NBTHK monthly exhibitions from 1998 to 2024.