Dai Hannya Nagamitsu

Dai Hannya Nagamitsu is a National Treasure tachi displayed at the Tokyo National Museum in Taitō. The blade measures 73.6 cm in length and shows a curvature of 2.9 cm, while the hamon patterns along the edge illustrate the forging technique from the 13th century.

Swordsmith Nagamitsu forged this weapon in the 13th century during the Kamakura era. It then belonged successively to Shogun Ashikaga Yoshiteru, warlord Oda Nobunaga, and the unifier Tokugawa Ieyasu.

The weapon's name ties Buddhist scholarship to its extraordinary worth, as it was equated with six hundred volumes of sacred texts during the 15th and 16th centuries. The valuation reflects how samurai viewed swords not merely as tools of battle but as spiritual and economic assets.

The sword is displayed in an exhibition area of the museum where the tempered zones and the ridge line become visible at close range. Visitors should allow enough time to perceive the details of the surface finish.

The great Kantō earthquake of 1923 damaged this weapon when the storage building collapsed. The subsequent restoration preserved the original form and structure, so today's visitors can view the work in its historical state.