Tachi vs Katana: The Definitive Guide to Japan's Two Great Sword Classifications

Two Great Sword Categories Often Confused

"Nihonto" broadly encompasses all Japanese swords, but the two primary historical categories — tachi and uchigatana (katana) — differ fundamentally in design philosophy, wearing method, curvature type, and historical context.

The Tachi: Mounted Warrior's Blade

Developed in the late Heian through Kamakura periods, the tachi was designed for mounted cavalry combat. Key characteristics: worn edge-down suspended from a cord (tachi-o) — koshi-zori curvature (peak near the base) optimizes the blade for downward cavalry strikes; blade length typically 73cm or more; signature inscribed on the outer face when worn (edge-down orientation). Outstanding tachi examples include the Dojikiri Yasunari (National Treasure, Tokyo National Museum), Mikazuki Munechika (National Treasure, TM), and Shishi-o associated with Minamoto no Yorimasa.

The Uchigatana: Infantry Warrior's Blade

The uchigatana (commonly called katana) emerged from the mid-Muromachi period to meet the demands of mass infantry combat in the Sengoku era. Key characteristics: worn edge-up thrust through the belt (sashi-omote); naka-zori curvature (peak at center); blade length 60–90cm; signature on the outer face when worn edge-up (opposite convention to tachi). Wearing edge-up enabled the development of iaijutsu — the technique of drawing and cutting in a single motion. In the peaceful Edo period, the daishō pairing of uchigatana with wakizashi became the formal mark of samurai status.

Practical Identification

In museum displays, check: which face bears the signature (tachi displayed edge-down show signatures; katana edge-up); curvature type (koshi-zori vs naka-zori); blade length. Many tachi were shortened (suriage) and reclassified as uchigatana in later periods — look for cut or folded-over signatures as evidence of modification.