The name Osafune Norimitsu spans a lineage of several generations within the Bizen Osafune group, extending from the late Kamakura period through the end of the Muromachi era. The progenitor is traditionally said to have been a disciple in the line of Nagamitsu, and an extant tanto dated Kagen 3 (1305) corroborates this early origin. Thereafter, surviving examples through the Nanbokucho period and into the Oei era are extremely few, and the line is thought to have lapsed before being revived in the Muromachi period. The smith most commonly encountered in extant works -- identified as the fourth generation in the meikan -- was active from around the Eikyo era through the Chokoku and Kansho eras. Together with Sukemitsu, this Norimitsu is celebrated as one of the twin peaks of so-called "Eikyo-Bizen," and his workmanship occupies the critical transitional phase between the Oei-Bizen manner and the later Sue-Bizen tradition. Within the Nanbokucho-period generation, one tradition holds that Norimitsu was either a disciple or a younger brother of Kanemitsu; dated works from the Jowa through Eiwa eras survive, and his style stands closest to Kanemitsu's within the group.

The characteristic hamon across the Norimitsu generations centers on koshi-biraki gunome -- gunome with valleys opened at the base -- mixed with choji, ko-gunome, togariba, and angular elements, forming the distinctive "crab-claw" (kani no tsume) appearance noted in the NBTHK setsumei. Ashi and yo enter well and frequently; the nioiguchi tends toward a tightened quality, with ko-nie forming; and the boshi enters in midare-komi, turning back either pointed or in ko-maru. The forging presents ko-itame-hada tightly packed, sometimes mixed with mokume; fine ji-nie adheres; chikei enters; and midare-utsuri stands out prominently -- a hallmark across nearly all designated examples. In the Nanbokucho-period works, the hamon broadens to a large-scale midare based on notare, with thicker nie, kinsuji, sunagashi, and tobiyaki; the manner closely approaches the level of Kanemitsu himself. The later Muromachi-period works, particularly those from around the Eisho era, show a midareba in which choji mingles vigorously with gunome, producing a florid, nioi-dominant character with bright nioiguchi.

Norimitsu's oeuvre encompasses tachi, katana, wakizashi, tanto, and naginata, with signed and dated examples providing an unusually continuous documentary record across the generations. The Tokubetsu-Juyo tachi bearing a Kyotoku 1 (1452) date, with its original kurijiri nakago and crisply surviving signature, is praised as the outstanding example among the fourth-generation works, preserved in fully intact condition. The Nanbokucho-period generation produced works of considerable scale, including blades originally exceeding 2 shaku 7 sun, with robust sugata and forceful boshi that convey an impression of martial power. Among the Sue-Bizen generation, Norimitsu's output is comparatively small, yet works from the Eisho era display a level of technique comparable to Yosozaemon-no-jo Sukesada and Jirozaemon-no-jo Katsumitsu, confirming his standing at the summit of the tradition. An Oei 33 (1426) tanto of exceptional documentary value fills a previously unknown gap in the lineage and demonstrates the elegant suguha with bo-utsuri that characterizes the school's quieter mode.