Nagasone Kotetsu and Kondō Isami — The Authenticity Dispute over the Shinsengumi Commander's Beloved Sword

Nagasone Okisato Nyūdō Kotetsu, commonly known as “Kotetsu,” was one of the representative swordsmiths of the early Edo period, and his works were known for a cutting edge so keen that they were rated as saijō ō-wazamono. In the Bakumatsu period, the tale that Kondō Isami, chief of the Shinsengumi, favored a Kotetsu blade is widely known. Yet whether the sword Kondō possessed was an authentic work has been debated from that time down to the present.

The Swordsmith Kotetsu

Nagasone Okisato is said to have come from Nagasone village in Ōmi Province (present-day Nagasone-chō, Hikone City, Shiga Prefecture), though there is also a theory that he was from Echizen. He was originally active in Echizen as an armorer (kacchūshi). He later moved to Edo and turned to sword-making, a career path unusual for the time. His experience handling iron as an armorer is said to have informed his swordmaking, and his works were highly valued as masterpieces that combined the beauty of the jigane with a sharp cutting edge. Although Kotetsu's period of active sword production was short, he established a reputation strong enough that he was later placed in the saijō ō-wazamono, the highest rank of battle-tested swords. Throughout the Edo period he won tremendous popularity among the samurai class.

The transition from armorer to swordsmith was unusual even at the time. In the early Edo period, the world was settling into peace while demand for armor still lingered, making it a transitional era. Okisato is thought to have initially made his living as an armorer. However, owing to changes in demand for swords and his own technical interests, he turned to swordmaking after reaching middle age, moved to Edo, and began to use the name Kotetsu. The leading view holds that his background as an armorer, who had broad experience in metalworking, provided the foundation that let him reach a high technical level despite his short period of production.

Because Kotetsu was so popular, counterfeit works and false signatures circulated widely even during his lifetime. So prevalent were fakes that a saying-like phrase, “If you see a Kotetsu, assume it is a fake,” was passed down in the sword world.

The story of the “Ishidōrō-giri Kotetsu” is known as an account conveying the cutting power of Kotetsu blades. When a thick pine branch in a garden was tested by cutting, the blade is said to have continued through and cut into a stone lantern placed beside it. Whether or not it is true, it is passed down as an anecdote that symbolizes the high regard in which people of the time held Kotetsu's cutting power. The accumulation of such stories gave the name Kotetsu itself a brand value, and it also became the soil for the later widespread use of false signatures.

Kondō Isami and the Kotetsu Anecdote

The tale that Kondō Isami, chief of the Shinsengumi, favored a Kotetsu has been handed down through Kondō's own letters and through testimony from those around him. It is said that when Kondō went to Kyoto, he asked sword dealers to procure a Kotetsu. However, because authentic Kotetsu works were already extremely rare at that time and difficult to obtain, the widely circulated theory is that a sword dealer sold Kondō a work by Minamoto Kiyomaro, passing it off as a Kotetsu.

It is unclear whether Kondō himself believed this sword was an authentic work, or whether he knew it was a fake but wore it to benefit from the reputation of the name “Kotetsu.” In any case, it is said that Kondō treated this sword as a Kotetsu for the rest of his life and carried it during major Shinsengumi activities, including the Ikedaya Incident.

The Authenticity Debate in Detail

The debate over Kondō's Kotetsu involves several theories. The first holds that Kondō's sword was a work of Minamoto Kiyomaro (a swordsmith representative of the Bakumatsu period, also called “Yotsuya Masamune”) with a forged Kotetsu signature cut into it. This theory rests on hearsay related by Nakayama Hakudō, a martial artist of the Meiji period, and on testimony from sword polisher (togishi) Inuzuka Tokutarō, among other sources. The second theory holds that an unsigned blade, which Saitō Hajime bought from an antique dealer in Kyoto, was regarded by Kondō as a Kotetsu and used by him. Satō Hikogorō is also said to have stated that Kondō's sword was unsigned. A third theory, that Kondō possessed an authentic Kotetsu, is also strongly maintained by some researchers and enthusiasts, but there is little conclusive physical evidence for it.

The sword Kondō wore has not been confirmed to survive, or its whereabouts are unknown. For this reason, a final resolution by scientific appraisal has not been reached at present. The authenticity debate therefore continues today, dependent on the interpretation of historical sources and the assessment of the reliability of the traditions.

Sword Trade and False Signatures in the Bakumatsu Period

The Kotetsu story of Kondō is important not merely as a question of the authenticity of one individual's sword, but as an example that symbolizes the actual state of the sword trading market in the Bakumatsu period. The Bakumatsu was a time when demand for swords among samurai and shishi rose sharply along with the rising movement for sonnō jōi. As a result, forgeries bearing the signatures of famous smiths circulated in large numbers. Kotetsu was among the smiths most targeted for this. The fact that a prominent figure such as Kondō sought a Kotetsu itself reveals the brand faith in swords and the actual state of forgery-based sales in that era.

Apart from Kondō, the Shinsengumi members had a strong inclination toward seeking famous swords, and senior members such as Hijikata Toshizō are also said to have each worn swords with venerable histories. This strong attachment to swords among Shinsengumi members is thought to have reflected not only practical necessity in combat, but also aspects of samurai dignity and self-presentation. The fact that Kondō sought the name Kotetsu itself suggests that, as head of the Shinsengumi organization, he placed importance on the symbolic authority conferred by wearing famous swords.

The Shinsengumi was originally a mixed force that included people of farming and townsman backgrounds, and Kondō himself came from a farming family in the Tama District of Musashi Province. For Kondō and others, who were not hereditary samurai by origin, carrying famous swords in Kyoto, the center of samurai society, is thought to have served to externally reinforce their standing as samurai. Seeking a sword bearing the name of Kotetsu, the foremost smith of the day, was also an attempt at personal identity certification that went beyond the simple choice of a practical weapon.

Later Influence

The Kondō–Kotetsu anecdote has been repeatedly featured in novels, films, manga, and dramas about the Shinsengumi since the Meiji period, and it has become firmly established as an indispensable element in describing the figure of Kondō Isami. Although the historical authenticity remains undetermined, the combination of “Kondō Isami's Kotetsu” is widely discussed among modern sword culture and history enthusiasts as a symbolic episode linking Japanese swords and late Tokugawa history. The anecdote is also a good example of how Japanese swords have functioned as more than mere practical weapons, bearing the authority, convictions, and narratives of their owners.