Tomomitsu was the son of Kanemitsu I and younger brother of Kanemitsu II. Of the four well-known Tomomitsu blades in existence, three are National Treasures in the possession of the Nikko Tosho-gu, Uesugi Jingu and the Keirin-ji temple; the fourth, classified an Important Art Object, is in a Japanese private collection. Tomomitsu's work is characterized by Osafune-style gonome midare with choji or midare and this example is executed in gonome midare with some ko-notare. The horimono here are well carved and placed so as not to detract from the blade itself; it was during this period (late Kamakura and Nambokucho) that the use of carved designs became more common, increasing in frequency towards the later Nambokucho and into the Muromachi period.

Tomimitsu's blades were frequently shortened; unshortened and fully dated blades are extremely rare.