Go-Toba-in is not a swordsmith in the ordinary sense but the Retired Emperor Go-Toba (後鳥羽上皇), the sovereign of the early Kamakura period who made the forge an imperial practice. The published sources state the tradition consistently: he selected the goban-kaji, the appointed smiths of his rotation, organized them into alternating shifts at the cloistered palace, and had swords forged there, and among these works the blades for which the Emperor himself performed the tempering are termed kiku-saku or gosaku[[c:1]]. The record is old. The NBTHK writes that his summoning of the master craftsmen of his day and his personal quenching of blades "has long been known from classical sword treatises, beginning with the Meizukushi" in the Kanchi-in manuscript, and the modern study Go-Toba-in Goban-kaji-ko collects the recorded works.

The defining mark is the chrysanthemum. The works are called kiku-saku because at the base of the ubu nakago, within the togidamari, they bear a finely incised sixteen- or twenty-four-petal chrysanthemum crest, and where the tang survives intact the worn kebori of the crest is still legible. The style, by contrast, is never his alone: the published sources repeat that the workmanship differs with the smith who served as the Emperor's counterpart on each occasion, some works resembling the Ko-Ichimonji, some in a Ko-Aoe manner, and some close to the working range of Awataguchi. What binds the group is the hallmark of the program: "in general they show yakiotoshi (焼落し), and from that area a mizukage-like effect often appears." At the dropped temper the nioiguchi weakens, so that at first glance the blade can suggest a retempered piece, and the published record is explicit that it is not. Among the surviving examples the sources distinguish a Kyoto style and a Bizen style.

The quiet side of the corpus is carried by the tachi handed down in the Yamauchi family, bearing the kiku-mon over a cipher-like character ichi[[c:2]] cut diagonally beneath it. The blade is slender, with high koshizori and funbari, inclining forward toward a small kissaki. Its jigane is itame mixed with mokume and flowing hada, the grain standing somewhat, with ji-nie and chikei, and toward the base a diagonal mizukage-like reflection rises. The temper is dropped above the machi with a koshiba-like flare; above it the hamon runs in a suguha tone with shallow notare, mixing ko-midare, ko-gunome and a ko-choji feeling. Small ashi enter and tobiyaki lie close to the edge, the whole well covered in nie with sunagashi and kinsuji; the boshi is sugu with ko-maru, strong in nie. The published sources place this work close to the Bizen Ko-Ichimonji school and read off the program's yakiotoshi and the mizukage-like utsuri at the base. The added ichi beneath the crest has no other recorded parallel among kiku-saku, "a precious piece of documentary material," and the blade carries a Hon'ami Kojo origami of Enpo 1 (1673) valuing it at 150 kan.

The flamboyant side is the tachi of the hatamoto Kuroda family, judged by the published sources to have had a Bizen smith as the counterpart. It is a dignified blade of nearly standard width with a marked taper, ample hiraniku, high curvature with koshizori and funbari, and a chu-kissaki. Here the jigane is a well forged ko-itame, the ji-nie dust-fine, and a vivid midare-utsuri stands out clearly. The yakiba is high, a flamboyant choji-midare with ashi and yo, nioi-dominant with ko-nie and an overall slanting tendency; tobiyaki mingle near the heads of the temper, and the nioiguchi is tight, bright and clear. Bonji are cut above the grooves, with gomabashi on the ura. The ji and ha are so robust (頗る健体) that the commentary records sensing a freshness at first glance, and it concludes that overall it is a splendid work and that the traditional attribution to kiku-gosaku may reasonably be accepted. The osuriage-mumei katana attributed to the group continue this Bizen manner, choji mixed with ko-midare, deep in nioi with yubashiri, sunagashi and kinsuji, the boshi midare-komi; on these the shortening has removed the yakiotoshi and the mizukage, and the appraisal rests on the archaic tone of the ji and ha. Of the Matsudaira blade Honma recorded that the attribution is appropriate and the workmanship good.

He left no pupils, and there is no downstream school. The lineage of a kiku-gosaku runs sideways, back to the school of the smith who attended the Emperor, and it is that resemblance, Ko-Ichimonji, Ko-Aoe or Awataguchi, joined to the crest, the yakiotoshi and the mizukage, that defines the group for appraisal. The published record also sets out the designated company these blades keep: among kiku-gosaku are a blade of the imperial collection and Important Cultural Properties from the former Echizen Matsudaira, Owari Tokugawa and Hayashibara collections, every one carrying the chrysanthemum cut into the tang.

Eleven designated works stand on record: four Important Cultural Properties, two blades recorded in the imperial collection, two Juyo Bijutsuhin, two Tokubetsu Juyo and one Juyo. Nine carry recorded provenance, and the roll is what an emperor's hand would lead one to expect. The Kuroda tachi was bestowed by Tokugawa Ieyasu on Kuroda Naotsuna in 1614 and was maintained every year through the Edo period by the shogunal sword office; the Itsukushima Shrine tachi is by shrine tradition a former possession of Ouchi Yoshitaka, dedicated by Mori Motonari, and suffered in the fire of Meiji 20 (1887); other blades passed through the Yamauchi, the Matsudaira and Echizen Matsudaira, the Kujo and the Imperial Family, and one came down from Uesugi Kagekatsu. Of recorded whereabouts the works rest at Itsukushima Shrine, the Tokyo and Kyoto National Museums and the Kurokawa Institute. The Important Cultural Properties and the imperial pieces are patrimony and will not trade; what remains to the private sphere is the small Tokubetsu Juyo and Juyo tier, three blades in all, so that a kiku-gosaku, the chrysanthemum of Go-Toba's own forge, coming into open hands is among the rarest encounters the field affords.

Go-Toba-in is not a swordsmith in the ordinary sense but the Retired Emperor Go-Toba (後鳥羽上皇), the sovereign of the early Kamakura period who made the forge an imperial practice. The published sources state the tradition consistently: he selected the goban-kaji, the appointed smiths of his rotation, organized them into alternating shifts at the cloistered palace, and had swords forged there, and among these works the blades for which the Emperor himself performed the tempering are termed kiku-saku or gosaku[[c:1]]. The record is old. The NBTHK writes that his summoning of the master craftsmen of his day and his personal quenching of blades "has long been known from classical sword treatises, beginning with the Meizukushi" in the Kanchi-in manuscript, and the modern study Go-Toba-in Goban-kaji-ko collects the recorded works.

The defining mark is the chrysanthemum. The works are called kiku-saku because at the base of the ubu nakago, within the togidamari, they bear a finely incised sixteen- or twenty-four-petal chrysanthemum crest, and where the tang survives intact the worn kebori of the crest is still legible. The style, by contrast, is never his alone: the published sources repeat that the workmanship differs with the smith who served as the Emperor's counterpart on each occasion, some works resembling the Ko-Ichimonji, some in a Ko-Aoe manner, and some close to the working range of Awataguchi. What binds the group is the hallmark of the program: "in general they show yakiotoshi (焼落し), and from that area a mizukage-like effect often appears." At the dropped temper the nioiguchi weakens, so that at first glance the blade can suggest a retempered piece, and the published record is explicit that it is not. Among the surviving examples the sources distinguish a Kyoto style and a Bizen style.

The quiet side of the corpus is carried by the tachi handed down in the Yamauchi family, bearing the kiku-mon over a cipher-like character ichi[[c:2]] cut diagonally beneath it. The blade is slender, with high koshizori and funbari, inclining forward toward a small kissaki. Its jigane is itame mixed with mokume and flowing hada, the grain standing somewhat, with ji-nie and chikei, and toward the base a diagonal mizukage-like reflection rises. The temper is dropped above the machi with a koshiba-like flare; above it the hamon runs in a suguha tone with shallow notare, mixing ko-midare, ko-gunome and a ko-choji feeling. Small ashi enter and tobiyaki lie close to the edge, the whole well covered in nie with sunagashi and kinsuji; the boshi is sugu with ko-maru, strong in nie. The published sources place this work close to the Bizen Ko-Ichimonji school and read off the program's yakiotoshi and the mizukage-like utsuri at the base. The added ichi beneath the crest has no other recorded parallel among kiku-saku, "a precious piece of documentary material," and the blade carries a Hon'ami Kojo origami of Enpo 1 (1673) valuing it at 150 kan.

The flamboyant side is the tachi of the hatamoto Kuroda family, judged by the published sources to have had a Bizen smith as the counterpart. It is a dignified blade of nearly standard width with a marked taper, ample hiraniku, high curvature with koshizori and funbari, and a chu-kissaki. Here the jigane is a well forged ko-itame, the ji-nie dust-fine, and a vivid midare-utsuri stands out clearly. The yakiba is high, a flamboyant choji-midare with ashi and yo, nioi-dominant with ko-nie and an overall slanting tendency; tobiyaki mingle near the heads of the temper, and the nioiguchi is tight, bright and clear. Bonji are cut above the grooves, with gomabashi on the ura. The ji and ha are so robust (頗る健体) that the commentary records sensing a freshness at first glance, and it concludes that overall it is a splendid work and that the traditional attribution to kiku-gosaku may reasonably be accepted. The osuriage-mumei katana attributed to the group continue this Bizen manner, choji mixed with ko-midare, deep in nioi with yubashiri, sunagashi and kinsuji, the boshi midare-komi; on these the shortening has removed the yakiotoshi and the mizukage, and the appraisal rests on the archaic tone of the ji and ha. Of the Matsudaira blade Honma recorded that the attribution is appropriate and the workmanship good.

He left no pupils, and there is no downstream school. The lineage of a kiku-gosaku runs sideways, back to the school of the smith who attended the Emperor, and it is that resemblance, Ko-Ichimonji, Ko-Aoe or Awataguchi, joined to the crest, the yakiotoshi and the mizukage, that defines the group for appraisal. The published record also sets out the designated company these blades keep: among kiku-gosaku are a blade of the imperial collection and Important Cultural Properties from the former Echizen Matsudaira, Owari Tokugawa and Hayashibara collections, every one carrying the chrysanthemum cut into the tang.

Eleven designated works stand on record: four Important Cultural Properties, two blades recorded in the imperial collection, two Juyo Bijutsuhin, two Tokubetsu Juyo and one Juyo. Nine carry recorded provenance, and the roll is what an emperor's hand would lead one to expect. The Kuroda tachi was bestowed by Tokugawa Ieyasu on Kuroda Naotsuna in 1614 and was maintained every year through the Edo period by the shogunal sword office; the Itsukushima Shrine tachi is by shrine tradition a former possession of Ouchi Yoshitaka, dedicated by Mori Motonari, and suffered in the fire of Meiji 20 (1887); other blades passed through the Yamauchi, the Matsudaira and Echizen Matsudaira, the Kujo and the Imperial Family, and one came down from Uesugi Kagekatsu. Of recorded whereabouts the works rest at Itsukushima Shrine, the Tokyo and Kyoto National Museums and the Kurokawa Institute. The Important Cultural Properties and the imperial pieces are patrimony and will not trade; what remains to the private sphere is the small Tokubetsu Juyo and Juyo tier, three blades in all, so that a kiku-gosaku, the chrysanthemum of Go-Toba's own forge, coming into open hands is among the rarest encounters the field affords.