A Japanese sword that is longer than
23.6" (60cm) and is worn in the belt with the edge up is called a Katana.
This conversion from Tachi to Katana probably began in the Muromachi period
(1392 - ) but became widely worn in the Shinto period. It became popular to
wear two swords in the thrust in the sash with the edges up. These two
swords together were known as a daisho or "large and small". The smaller of
the two swords was called a wakizashi.