Omote and Ura side Katana
A Japanese katana has two sides, this of course also affects the Tsuka (handle). The side of the handle to the outside, away from the body, is the Omote side. The Ura side is the opposite, this side "looks" at the body when the Katana or Iaito is worn. It is very important how the katana of tachi is worn, which for a tachi is with the Ha of edge site down, so for a tachi everything is opposite.
Omote and Ura concept are familiar inside the martial arts. Omote is the visible, the obvious or what is easily reachable. Ura is secret, hidden, invisible and reverse of omote. In specific situations, it also refers to the esoteric understanding of a a situation.
A Zen story: everyday, a young disciple from a martial art would walk across a small garden on his way home after training. One day, he notices a beautiful flower and thanks it for blooming in his garden. But the flower has always been there; he simply never noticed it until the day he changed level of consciousness in his training. The flower was "hidden" (ura) in his reality but had been there all along in the obvious (omote).
Omote side katana