Uda Kunimitsu (宇多国光), known as Ko-nyudo Kunimitsu (古入道国光), is traditionally regarded as the founder of the Uda school. According to accepted tradition, around the Bunpo era (1317–1319) he relocated from Uda District in Yamato Province to Utsu in Etchu Province, establishing a lineage that would flourish through subsequent generations. He is said to have had sons named Kunifusa and Kunimune, and subsequent smiths bearing the name Kunimitsu appear to span several generations from the late Kamakura into the Nanbokucho period. No definitively signed works by Ko-nyudo Kunimitsu himself are confirmed; however, extant tachi bearing the signature "Uda Kunimitsu" and datable to the late Kamakura period are reasonably attributed to his hand.

Blades attributed to Ko-nyudo Kunimitsu strongly display a Yamato-like character in both jihada and hamon. The forging typically shows tightly worked ko-itame-hada, at times with masame-hada mixed in toward the edge, well covered with ji-nie and intermingled with chikei. A whitish utsuri reminiscent of shirake may stand out in the ji. The hamon is characteristically suguha-based, occasionally exhibiting shallow notare with a slight admixture of small gunome; ko-nie adheres well, and sunagashi and kinsuji appear along the temper line. The boshi returns in ko-maru with hakikake at the tip. Bo-hi carved on both sides with maru-dome is a recurring feature.

Ko-nyudo Kunimitsu occupies a position of considerable importance as the progenitor of the Uda school, one of the principal forging traditions of Etchu Province. His work demonstrates the direct transmission of Yamato-den characteristics into a provincial setting during the late Kamakura period. Blades attributed to his hand that survive in kenzen condition constitute valuable reference material for understanding the formative period of the Uda tradition and the broader dissemination of Yamato forging methods into the northern provinces.