Sadazane is one of the earliest of the Ichimonji smiths of Bizen, working in the early Kamakura period about the Hoji era of 1247 to 1249. The Meikan records him as a son of the Fukuoka Ichimonji founder Munetada, a line of descent the published sources repeat in their commentary on his blades, while a second tradition makes him a son of the Ko-Bizen smith Takatsuna. The published record sets the parentage against the work and finds them at odds: his surviving tachi, the commentary says again and again, fire a well-nie-laden ko-midare with no prominent reflection in the ji, so that they look more archaic than Munetada, "older in feeling than Munetada"[[c:1]]. For that reason some judges classed him not with the Ichimonji at all but with the older Ko-Bizen group, and the question of which side a given blade belongs to runs through his whole record. The point was settled by direct observation. The reference texts preserve Honma's note that he had examined examples carrying the character ichi above the two-character signature, "and so it is beyond doubt Ko-Ichimonji"[[c:2]], placing Sadazane at the very head of the school.

His characteristic hand is the quiet, archaic register the published sources treat as typical. Over a fine ko-itame the temper is a suguha-based ko-midare with ko-choji, ashi and yo entering freely, the nioiguchi bright, ko-nie gathering with kinsuji and sunagashi coming and going, and the boshi running quietly to a small ko-maru turnback or burning out without one. What sets him apart is what is missing. Where the Ichimonji norm is a midare-utsuri standing vividly in the ji, the commentary records of Sadazane that the reflection is not prominent, and one Juyo note draws the contrast as his individuality: the Ko-Ichimonji blades mostly show a standing utsuri, "yet this smith has many works in which the reflection is not conspicuous"[[c:3]], and from this his own character can be read. The suguha base under the small midare, the restraint of the temper, and the absence of the showy reflection are the marks that the published sources return to as his typical work.

The jigane is the other half of the picture. The forging is a ko-itame, at times a itame with a standing tendency and flowing passages, very well knit, with ji-nie lying thick and fine and chikei entering through it. Through that jigane the published sources repeatedly note patches of jifu, the speckled steel of old Bizen and Aoe, and on one Tokubetsu Juyo tachi the commentary writes that the itame stands a little and carries ji-nie thickly with "jifu mixed in that at a glance recalls Aoe"[[c:4]]. That speckled steel, rare among the brilliant Fukuoka and Katayama hands, is the most particular thing in his ji. On the finer-grained blades the same feature reads as a faint jifu-toned utsuri, present but never the bright, billowing reflection of the later Ichimonji.

His work falls into two registers of one manner. The typical one is the subdued ko-midare described above. A minority of his tachi show a somewhat showier hand, and the published sources flag the difference explicitly: of one Juyo tachi with a midare-utsuri standing and a choji-midare crossed with gunome, the commentary says it is "somewhat flamboyant for Sadazane"[[c:5]]. Of a Tokubetsu Juyo tachi in the same fuller voice, the published record observes that it "carries on the manner of Ko-Bizen and adds a further freshness to it"[[c:6]], and finds in that the very thing worth seeing in the Ko-Ichimonji school. The signature itself is part of his identity. The mei is a two-character Sadazane cut large near the mune in a thin chisel, "large in thin strokes"[[c:7]], and the published sources name this hosotagane large two-character signature as one of the smith's own tells, a help in attribution given how few signed works survive.

The difficulty that defines his place in the school is the homonym. The published sources record that there is a Sadazane in both the Ko-Bizen group and the early Ichimonji "whose work and signature so resemble each other that they cannot readily be told apart"[[c:8]], and individual blades are judged to one side or the other case by case. Several of his Juyo tachi are read as Ko-Bizen work, others firmly as Ko-Ichimonji; the ichi-marked examples Honma saw anchor the Ichimonji end. The commentary frames his restraint as the school's virtue rather than a want of fire, noting of one blade that the subdued character is not Sadazane's alone but belongs to the whole early group, "and that everything is understated is itself a point to see"[[c:9]]. He stands at the threshold where Ko-Bizen passes into Ichimonji, his archaic ko-midare preceding the brilliant Fukuoka choji of Yoshifusa and the Katayama hand of Norifusa, and his blades are valued as records of the school at its very beginning.

Sadazane is rated Jo saku by Fujishiro, with a Toko Taikan valuation of 1,200,000 yen. Almost his whole surviving record is signed, an unusual circumstance for so early a Bizen master: twelve of his designated works carry his two-character mei against a single unsigned attribution. The designations stand at four Tokubetsu Juyo and seven Juyo, eleven blades in the Tokubetsu Juyo and Juyo tiers, with one Important Cultural Property among them. The earliest, a tachi designated Juyo Bijutsuhin in 1939, is the blade the reference texts cite under Honma's ichi-mark note; it was held by Kazama Yokichi of Niigata. Among his Juyo the published sources single out one as "the foremost of the Ko-Ichimonji within the Important Sword rank"[[c:10]], and of his finest Juyo tachi the commentary calls it, "a valuable blade by which to know this smith's real ability, signed works by him being few"[[c:11]]. Recorded whereabouts of his blades include the Tokugawa Art Museum, the Tokyo National Museum and the Seikado Bunko Art Museum, the rest held in long-private hands. With one Important Cultural Property preserved as patrimony and never traded, his market is the small body of Tokubetsu Juyo and Juyo tachi; a signed Sadazane comes to light only rarely, and when one does it is a record of the earliest Ichimonji generation that few collectors will encounter.

Sadazane is one of the earliest of the Ichimonji smiths of Bizen, working in the early Kamakura period about the Hoji era of 1247 to 1249. The Meikan records him as a son of the Fukuoka Ichimonji founder Munetada, a line of descent the published sources repeat in their commentary on his blades, while a second tradition makes him a son of the Ko-Bizen smith Takatsuna. The published record sets the parentage against the work and finds them at odds: his surviving tachi, the commentary says again and again, fire a well-nie-laden ko-midare with no prominent reflection in the ji, so that they look more archaic than Munetada, "older in feeling than Munetada"[[c:1]]. For that reason some judges classed him not with the Ichimonji at all but with the older Ko-Bizen group, and the question of which side a given blade belongs to runs through his whole record. The point was settled by direct observation. The reference texts preserve Honma's note that he had examined examples carrying the character ichi above the two-character signature, "and so it is beyond doubt Ko-Ichimonji"[[c:2]], placing Sadazane at the very head of the school.

His characteristic hand is the quiet, archaic register the published sources treat as typical. Over a fine ko-itame the temper is a suguha-based ko-midare with ko-choji, ashi and yo entering freely, the nioiguchi bright, ko-nie gathering with kinsuji and sunagashi coming and going, and the boshi running quietly to a small ko-maru turnback or burning out without one. What sets him apart is what is missing. Where the Ichimonji norm is a midare-utsuri standing vividly in the ji, the commentary records of Sadazane that the reflection is not prominent, and one Juyo note draws the contrast as his individuality: the Ko-Ichimonji blades mostly show a standing utsuri, "yet this smith has many works in which the reflection is not conspicuous"[[c:3]], and from this his own character can be read. The suguha base under the small midare, the restraint of the temper, and the absence of the showy reflection are the marks that the published sources return to as his typical work.

The jigane is the other half of the picture. The forging is a ko-itame, at times a itame with a standing tendency and flowing passages, very well knit, with ji-nie lying thick and fine and chikei entering through it. Through that jigane the published sources repeatedly note patches of jifu, the speckled steel of old Bizen and Aoe, and on one Tokubetsu Juyo tachi the commentary writes that the itame stands a little and carries ji-nie thickly with "jifu mixed in that at a glance recalls Aoe"[[c:4]]. That speckled steel, rare among the brilliant Fukuoka and Katayama hands, is the most particular thing in his ji. On the finer-grained blades the same feature reads as a faint jifu-toned utsuri, present but never the bright, billowing reflection of the later Ichimonji.

His work falls into two registers of one manner. The typical one is the subdued ko-midare described above. A minority of his tachi show a somewhat showier hand, and the published sources flag the difference explicitly: of one Juyo tachi with a midare-utsuri standing and a choji-midare crossed with gunome, the commentary says it is "somewhat flamboyant for Sadazane"[[c:5]]. Of a Tokubetsu Juyo tachi in the same fuller voice, the published record observes that it "carries on the manner of Ko-Bizen and adds a further freshness to it"[[c:6]], and finds in that the very thing worth seeing in the Ko-Ichimonji school. The signature itself is part of his identity. The mei is a two-character Sadazane cut large near the mune in a thin chisel, "large in thin strokes"[[c:7]], and the published sources name this hosotagane large two-character signature as one of the smith's own tells, a help in attribution given how few signed works survive.

The difficulty that defines his place in the school is the homonym. The published sources record that there is a Sadazane in both the Ko-Bizen group and the early Ichimonji "whose work and signature so resemble each other that they cannot readily be told apart"[[c:8]], and individual blades are judged to one side or the other case by case. Several of his Juyo tachi are read as Ko-Bizen work, others firmly as Ko-Ichimonji; the ichi-marked examples Honma saw anchor the Ichimonji end. The commentary frames his restraint as the school's virtue rather than a want of fire, noting of one blade that the subdued character is not Sadazane's alone but belongs to the whole early group, "and that everything is understated is itself a point to see"[[c:9]]. He stands at the threshold where Ko-Bizen passes into Ichimonji, his archaic ko-midare preceding the brilliant Fukuoka choji of Yoshifusa and the Katayama hand of Norifusa, and his blades are valued as records of the school at its very beginning.

Sadazane is rated Jo saku by Fujishiro, with a Toko Taikan valuation of 1,200,000 yen. Almost his whole surviving record is signed, an unusual circumstance for so early a Bizen master: twelve of his designated works carry his two-character mei against a single unsigned attribution. The designations stand at four Tokubetsu Juyo and seven Juyo, eleven blades in the Tokubetsu Juyo and Juyo tiers, with one Important Cultural Property among them. The earliest, a tachi designated Juyo Bijutsuhin in 1939, is the blade the reference texts cite under Honma's ichi-mark note; it was held by Kazama Yokichi of Niigata. Among his Juyo the published sources single out one as "the foremost of the Ko-Ichimonji within the Important Sword rank"[[c:10]], and of his finest Juyo tachi the commentary calls it, "a valuable blade by which to know this smith's real ability, signed works by him being few"[[c:11]]. Recorded whereabouts of his blades include the Tokugawa Art Museum, the Tokyo National Museum and the Seikado Bunko Art Museum, the rest held in long-private hands. With one Important Cultural Property preserved as patrimony and never traded, his market is the small body of Tokubetsu Juyo and Juyo tachi; a signed Sadazane comes to light only rarely, and when one does it is a record of the earliest Ichimonji generation that few collectors will encounter.