O-katana
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An O-Katana (太刀) is a katana slightly longer than a regular katana (O meaning great or long in Japanese). These are not to be confused with the great Nodachi, which were significantly longer than katana. O-katana were most often katana made for a person of great stature. These blades were somewhat common during the Old Sword/Koto period (900 to 1530) and less common during the New Sword/Shinto period (1531 to 1867). Blades of this type were difficult to forge equally from tip to base, due to the great length. Often tachi made during the Koto period were of this length.