Tsunemitsu (恒光) was a swordsmith of the Masatsune lineage, traditionally regarded as either the son or a disciple of Masatsune (正恒). Active from the late period, the lineage is documented as continuing through the era; a dated work bearing the inscription Shoan 3 (1301) provides important evidence that the manner persisted uninterrupted into the late period. Extant signed works by Tsunemitsu are comparatively few, lending particular documentary value to those blades that preserve with legible signatures.
Tsunemitsu's forging is characteristically a tightly worked or , at times with slight admixture of , producing abundant and . A faint is frequently observed. The typically proceeds as a -based mixed with and , enriched by , , and well-adhering , with and enlivening the . Certain works display a distinctive rise at the in a -like manner before settling into small irregularities above. The is consistently with or , and the overall exhibits pronounced with and a compact , preserving the elegant classical silhouette of the late tradition. In both and , the workmanship shares recognizable characteristics with Masatsune, fully supporting the attribution to that line.
Tsunemitsu's blades are esteemed for their dignified form and superior preservation, with several bearing distinguished provenance including transmission within the Daishoji Maeda family of Province and appraisals. The combination of archaic elegance in shape and refined workmanship in and places Tsunemitsu among the notable smiths of the school, and surviving signed examples constitute valuable reference material for the study of early swordsmithing.