Tantō

A tantō ( 短刀 ) is simply a small katana . Several chūnin , medical-nin , and shinobi of Konohagakure wear them strapped to their lower backs when going into battle. The version Root uses is straight and double-edged with no tip, meant only for cutting and defence. They carry the tantō vertically on the back, specifically behind the shoulder; Sai is one of the notable ones that uses the tantō, which he carries on his back behind the right shoulder. Sakumo — and Kakashi Hatake after inheriting it — carried a special tantō, known as the White Light Chakra Sabre . Gamabunta and Gamakichi also carry these, albeit gigantic versions that fit their size.