A tanto dated Shohei 17 (1362) and signed Choshu ju Yasuyoshi[[c:1]], today a Juyo Bijutsuhin, anchors nearly everything the published sources say about Yasuyoshi of Chikuzen. Its hand is identical to his customary signature, and on that identity rests the account repeated at the head of entry after entry: Yasuyoshi was the son of O-Sa (大左), succeeded him as the second generation of the Samonji line, and later moved from Chikuzen to Nagato. His dated work runs from Shohei 17 into the Joji era. The name did not end with him, for descendants or pupils carried it in Nagato into the early Muromachi period, the line the sources call Choshu-Sa (長州左). Across half a century of designations the NBTHK assigns him one constant character, stated in almost the same words each time: his is the work in which, "within the Sa family a Bizen temperament intermingles"[[c:2]].

The signed record has a strict shape. Every signed Yasuyoshi is a wide, sunnobi tanto or ko-wakizashi in hira-zukuri, thin in kasane and shallow in sori, the full mid-Nanbokucho stance; where O-Sa's tanto stay small, his run large. The published sources state plainly that no authenticated signed tachi exists, so his tachi and naginata survive as osuriage mumei attributions. The mei itself is a large two-character signature cut with a somewhat thick chisel below the mekugi-ana at the center of the nakago. On occasion it is prefixed with the character Sa, a form headed by the meibutsu Hitotsuyanagi Yasuyoshi (一柳安吉), an Important Cultural Property. The record is just as exact about an absence: works signed Sa Yasuyoshi (左安吉) and Choshu ju Yasuyoshi both survive, but "one does not see examples signed Chikushu ju Yasuyoshi"[[c:3]].

His jigane is an itame that flows and often stands, mixed with mokume, with ji-nie attached. Over it rises a whitish shirake-utsuri, a bo-utsuri, or a sugu-utsuri near the edge, and the published sources name this flowing, standing forging with its whitish cast the viewing point of the smith. The hamon is a shallow ko-notare mixed with gunome, ko-gunome and pointed elements, nioi-dominant with ko-nie. Ashi enter, fine sunagashi runs through, and kinsuji appear here and there. The boshi runs midare-komi or thrusts up in tsukiage fashion, leans slightly toward the edge, and ends pointed with light hakikake and a rather long return. Set against his father the judgment is plain: the brilliance of ji and ha falls short of O-Sa, one early entry stating without ceremony that "his skill as well does not reach his father"[[c:4]], and the boshi, lacking O-Sa's sharpness, often falls into a leaning tendency. These same qualities form the stated kantei trap. Nioi-dominant with ko-nie set in, his work "at first sight strays among Osafune pieces such as Kanemitsu"[[c:5]], and the standing utsuri only strengthens the impression.

Two registers complicate the portrait at its edges. A minority of his smallest tanto, nearly O-Sa's own size with a slightly withered fukura, keep close to the master: dust-fine thick ji-nie, fine chikei, at times a nie-utsuri, a bright clear nioiguchi with kinsuji and sunagashi sweeping through, the boshi pointed, a make the published sources call "truly mistakable for O-Sa"[[c:6]]. On the Tokubetsu Juyo tanto signed Sa Yasuyoshi, the character Sa is fluent and close to O-Sa's own hand while the two characters of Yasuyoshi show a somewhat naive chisel; whether such pieces prove the tradition that O-Sa himself signed Yasuyoshi in his last years, or are instead Yasuyoshi's earliest work, the NBTHK leaves open for future study. At the other edge stand the Nagato years. Blades read as the Nanbokucho Choshu Yasuyoshi differ from his usual nioi-dominant hand: ji and ha take nie strongly, the notare grows bold with kuichigai-ba mixing in, sunagashi sweeps with kinsuji entering, and the boshi thrusts up to a point. Oei-dated work is judged plainly a successor generation, while the Eiwa-dated pieces stand unresolved between the founder's last years and a second generation, a question the published sources repeat as a subject for future research.

On unsigned blades of the Sa type his own marks decide the attribution. Where the flowing, standing itame carries a whitish utsuri, where the temper turns nioi-dominant in small patterns, and where the thrusting pointed boshi softens into a lean, the work is likened to Yasuyoshi within the school, and several osuriage katana have been so appraised. The pointed boshi is the Sa-family inheritance he never gives up; the softness of the edge is his own. The recent entries single out "the deep nioiguchi carrying a soft feeling"[[c:7]] and the rich activity working inside the ha, finding in them a strength that remains his even where the brilliance does not match his father's.

Fujishiro rates him Jo-jo saku, and the record is unusually legible: forty-five designated works are on record, thirty-six of them signed against seven unsigned. Six blades are Important Cultural Properties, headed by the meibutsu Hitotsuyanagi Yasuyoshi; four are Juyo Bijutsuhin, among them the dated Shohei 17 tanto; and thirty-three stand in the Tokubetsu Juyo and Juyo tiers, one Tokubetsu Juyo wakizashi praised as "the very finest within this smith's work"[[c:8]]. Fourteen blades carry recorded provenance: examples passed in the Bizen Ikeda and Inshu Ikeda houses, the Tosa Yamauchi and the Maeda, one tanto certified in the ownership of Tokugawa Iesato, and another treasured by Motoda Nagazane, the Confucian scholar of Kumamoto. Of recorded whereabouts today, blades rest in the Tokugawa Art Museum, the Fukuoka City Museum, the Tokyo National Museum and the Sano Art Museum. The Important Cultural Properties are patrimony and will remain where they are; much of the rest is held by institutions or in long private keeping, and a signed Yasuyoshi coming into open hands is an uncommon event, appearing only rarely and rewarding patience.

A tanto dated Shohei 17 (1362) and signed Choshu ju Yasuyoshi[[c:1]], today a Juyo Bijutsuhin, anchors nearly everything the published sources say about Yasuyoshi of Chikuzen. Its hand is identical to his customary signature, and on that identity rests the account repeated at the head of entry after entry: Yasuyoshi was the son of O-Sa (大左), succeeded him as the second generation of the Samonji line, and later moved from Chikuzen to Nagato. His dated work runs from Shohei 17 into the Joji era. The name did not end with him, for descendants or pupils carried it in Nagato into the early Muromachi period, the line the sources call Choshu-Sa (長州左). Across half a century of designations the NBTHK assigns him one constant character, stated in almost the same words each time: his is the work in which, "within the Sa family a Bizen temperament intermingles"[[c:2]].

The signed record has a strict shape. Every signed Yasuyoshi is a wide, sunnobi tanto or ko-wakizashi in hira-zukuri, thin in kasane and shallow in sori, the full mid-Nanbokucho stance; where O-Sa's tanto stay small, his run large. The published sources state plainly that no authenticated signed tachi exists, so his tachi and naginata survive as osuriage mumei attributions. The mei itself is a large two-character signature cut with a somewhat thick chisel below the mekugi-ana at the center of the nakago. On occasion it is prefixed with the character Sa, a form headed by the meibutsu Hitotsuyanagi Yasuyoshi (一柳安吉), an Important Cultural Property. The record is just as exact about an absence: works signed Sa Yasuyoshi (左安吉) and Choshu ju Yasuyoshi both survive, but "one does not see examples signed Chikushu ju Yasuyoshi"[[c:3]].

His jigane is an itame that flows and often stands, mixed with mokume, with ji-nie attached. Over it rises a whitish shirake-utsuri, a bo-utsuri, or a sugu-utsuri near the edge, and the published sources name this flowing, standing forging with its whitish cast the viewing point of the smith. The hamon is a shallow ko-notare mixed with gunome, ko-gunome and pointed elements, nioi-dominant with ko-nie. Ashi enter, fine sunagashi runs through, and kinsuji appear here and there. The boshi runs midare-komi or thrusts up in tsukiage fashion, leans slightly toward the edge, and ends pointed with light hakikake and a rather long return. Set against his father the judgment is plain: the brilliance of ji and ha falls short of O-Sa, one early entry stating without ceremony that "his skill as well does not reach his father"[[c:4]], and the boshi, lacking O-Sa's sharpness, often falls into a leaning tendency. These same qualities form the stated kantei trap. Nioi-dominant with ko-nie set in, his work "at first sight strays among Osafune pieces such as Kanemitsu"[[c:5]], and the standing utsuri only strengthens the impression.

Two registers complicate the portrait at its edges. A minority of his smallest tanto, nearly O-Sa's own size with a slightly withered fukura, keep close to the master: dust-fine thick ji-nie, fine chikei, at times a nie-utsuri, a bright clear nioiguchi with kinsuji and sunagashi sweeping through, the boshi pointed, a make the published sources call "truly mistakable for O-Sa"[[c:6]]. On the Tokubetsu Juyo tanto signed Sa Yasuyoshi, the character Sa is fluent and close to O-Sa's own hand while the two characters of Yasuyoshi show a somewhat naive chisel; whether such pieces prove the tradition that O-Sa himself signed Yasuyoshi in his last years, or are instead Yasuyoshi's earliest work, the NBTHK leaves open for future study. At the other edge stand the Nagato years. Blades read as the Nanbokucho Choshu Yasuyoshi differ from his usual nioi-dominant hand: ji and ha take nie strongly, the notare grows bold with kuichigai-ba mixing in, sunagashi sweeps with kinsuji entering, and the boshi thrusts up to a point. Oei-dated work is judged plainly a successor generation, while the Eiwa-dated pieces stand unresolved between the founder's last years and a second generation, a question the published sources repeat as a subject for future research.

On unsigned blades of the Sa type his own marks decide the attribution. Where the flowing, standing itame carries a whitish utsuri, where the temper turns nioi-dominant in small patterns, and where the thrusting pointed boshi softens into a lean, the work is likened to Yasuyoshi within the school, and several osuriage katana have been so appraised. The pointed boshi is the Sa-family inheritance he never gives up; the softness of the edge is his own. The recent entries single out "the deep nioiguchi carrying a soft feeling"[[c:7]] and the rich activity working inside the ha, finding in them a strength that remains his even where the brilliance does not match his father's.

Fujishiro rates him Jo-jo saku, and the record is unusually legible: forty-five designated works are on record, thirty-six of them signed against seven unsigned. Six blades are Important Cultural Properties, headed by the meibutsu Hitotsuyanagi Yasuyoshi; four are Juyo Bijutsuhin, among them the dated Shohei 17 tanto; and thirty-three stand in the Tokubetsu Juyo and Juyo tiers, one Tokubetsu Juyo wakizashi praised as "the very finest within this smith's work"[[c:8]]. Fourteen blades carry recorded provenance: examples passed in the Bizen Ikeda and Inshu Ikeda houses, the Tosa Yamauchi and the Maeda, one tanto certified in the ownership of Tokugawa Iesato, and another treasured by Motoda Nagazane, the Confucian scholar of Kumamoto. Of recorded whereabouts today, blades rest in the Tokugawa Art Museum, the Fukuoka City Museum, the Tokyo National Museum and the Sano Art Museum. The Important Cultural Properties are patrimony and will remain where they are; much of the rest is held by institutions or in long private keeping, and a signed Yasuyoshi coming into open hands is an uncommon event, appearing only rarely and rewarding patience.