Name: Japanese Blades UK
Address: GB
Price range: £££

Before there was an Ichimonji school or an Osafune mainline, there was Ko-Bizen, and at its head stand two names: Tomonari and Masatsune. They worked in Bizen province in the late Heian period, when the curved tachi was still a young form, and the blades attributed to them are the fountainhead from which the entire Bizen tradition flows. “Ko-Bizen” (old Bizen) is best understood not as one man but as the early group these two define, the spring from which the longest and most productive river in nihonto runs.

History and lineage

Tradition places Tomonari around 987 to 989 and Masatsune a little after, around 995 to 999, though Heian dating of this kind is approximate and several generations may have signed each name across the decades. Both belong to the loose body of early-Bizen smiths working before the school’s Kamakura expansion, makers of swords for the mounted warfare of the late Heian court and its provincial allies. The line they begin runs forward through the Kamakura flowering of the Ichimonji group and on into the Osafune mainline, whose founder Mitsutada drew directly on Ko-Bizen models in shaping his own work. To call Tomonari and Masatsune founder-smiths is therefore not quite to call them individuals so much as the two clearest hands in the group that opens the whole tradition.

Identifying characteristics

The Ko-Bizen sugata is slender and graceful, a Heian tachi with a deep koshizori, the curve set low toward the hilt, and a small ko-kissaki. The temper is quiet and antique: ko-midare mixed with ko-chōji, worked in soft ko-nie along a gentle nioi-guchi, far more restrained than the towering chōji the school would later produce. The hada is a fine itame, sometimes with mokume, and the characteristic reflection in the ji is jifu-utsuri, a misty, patchy form of utsuri named for its cloud-like figures. Within the pair, tradition holds that Masatsune leans a touch more toward clustered ko-chōji while Tomonari is regarded as the most refined of the Ko-Bizen designers, his shapes the most quietly perfect. The overall impression is elegance and age, refinement rather than display.

Why this matters for collectors

Among the early masters Masatsune holds the highest current statutory count: by most counts around six National Treasure (Kokuhō) blades on the current list, with sources differing slightly on the figure. Tomonari is the less numerous in designations but is widely regarded as the finer designer of the two, and a signed tachi of his is held by the Tokyo National Museum. For the collector this places genuine signed work almost entirely beyond the market, in museums and the great collections. Anything offered as Ko-Bizen at this level will rest on kantei and will need NBTHK papers to be taken seriously, since a slender Heian shape with some utsuri is suggestive but not by itself sufficient. The character of the jifu-utsuri, the softness of the ko-nie, and the antique quiet of the ko-midare all have to cohere. The tradition Tomonari and Masatsune begin can be followed forward through Ichimonji, the Osafune line, and its founder Mitsutada, all set within the broader Bizen story.

If you’re considering a tachi attributed to Ko-Bizen, to Tomonari, or to Masatsune, we welcome enquiries, and we would always counsel proper papers before any commitment.