The origins of the tachi, a type of Japanese sword, can be traced back to ancient Japan. The exact individual or group responsible for creating the first tachi is not definitively known, as it emerged during a period of Japanese history when written records were scarce. However, it is believed that the tachi evolved from earlier sword designs influenced by neighboring cultures like China and Korea.

The tachi emerged in the Heian period (794-1185) and was used predominantly by samurai warriors. It featured a curved blade, a single-edged cutting edge, and was typically worn suspended from the belt, with the cutting edge facing downward. The tachi's design and usage evolved over time, and it eventually gave way to the development of the more commonly recognized katana during the Muromachi period (1336-1573).

It's important to note that the development of Japanese swords, including the tachi, was a result of continuous refinement and innovation by numerous swordsmiths and artisans over many generations. The first tachi was likely an evolution of earlier sword designs and techniques that were adapted and refined by skilled swordsmiths during that time.