A tantō is simply a small katana. Several chūnin, medical-nin and shinobi of Konohagakure when going to war wear them strapped to their lower backs. The version Root uses are double-edged and have 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 Hatake and Kakashi Hatake in his childhood carried a special tantō, known as the White Light Chakra Sabre. Gamabunta also carries one, albeit a gigantic version that fits his size.