Three smiths working at the village of Osafune across the second half of the thirteenth century set the terms for every Bizen blade that followed: Mitsutada the founder, his son Nagamitsu, and the closely related Sanenaga, the Sansaku triumvirate whose work opens this phase. Their window runs from the mid-Kamakura period into the early fourteenth century, when leadership passed to Nagamitsu's son Kagemitsu, the third-generation head whose dated tachi, naginata, and tanto carry the phase to its close around the Kenmu years. The setsumei repeatedly fix Kagemitsu by genealogy and date, citing pieces inscribed from Gen'o 1 (1319) and Genko 1 (1321) through Shochu and Kenmu (1325 to 1334); these ubu or lightly shortened, date-bearing blades are what give the founding chapter its firm chronological spine and separate it from the workshop-broad output of the later Nanbokucho and Oei generations. This is the orthodox mainline before the school fanned out: the generation that built the standard, not the ones that later reinterpreted it. The constructional signature of the phase is a tightly packed ko-itame, at times mixed with mokume, carrying fine ji-nie in dense particles, fine chikei, and a vivid midare-utsuri that the examiners single out again and again; one Kagemitsu tachi even pushes the utsuri toward a striped, Aoe-like dan-utsuri with reverse-slanting dark bands. Against the Ko-Bizen root, with its standing jifu-utsuri and thicker ha-nie, this phase reads as more refined and more tightly controlled in the ji. The temper marks the phase's internal turn.
Where Nagamitsu and Mitsutada favored flamboyant choji-midare, Kagemitsu pulls the hand inward to a suguha-based temper carrying ko-gunome, ko-choji, and angular elements, often with a reverse (saka-gakari) tendency, in a nioi-dominant, bright nioiguchi; the setsumei credit him specifically with perfecting kata-ochi gunome, the dropped-shoulder pattern repeatedly named as his completion. The boshi is the gentle sansaku-boshi, a shallow midare-komi or notare turning back in ko-maru. None of this is the powerful nie, scattered tobiyaki, and Soshu-den drama of the later Soden-Bizen, nor the open gunome and pointed candlewick boshi of the Oei revival; it is calmer, nioi-bound, and date-anchored. A collector separates this phase by its named masters and the kantei points the setsumei make explicit: kata-ochi gunome and the sansaku-boshi read Kagemitsu, while reverse-slanting jihan-utsuri and certain boshi forms let the examiners assign proxy daimei hands such as Chikakage and the collaborator Kagemasa, the latter named in a Shochu 2 (1325) joint tachi dedicated to Chichibu Shrine. Tanto are a discriminator in their own right, surviving in number for Kagemitsu where they are scarce for Nagamitsu, including the kanmuri-otoshi and hira-zukuri pieces with devotional bonji and kurikara carvings. Provenance present in the sample carries weight: a Kagemitsu tachi transmitted in the Chikuzen Kuroda family with its old scabbard, an orikaeshi-mei katana recorded in the Shimazu line, and tanto and tachi held in the Imperial collection where Kagemitsu is ranked beside Yoshimitsu, Shintogo Kunishige, and Samonji. These are the works that define the founding core against everything Osafune later became. Learn more →
