Dōjigiri Yasutsuna
童子切安綱 (Dōjigiri Yasutsuna)
The tachi by Yasutsuna of Hōki, the oldest of the tenka goken and one of the great treasures of the Japanese sword.
History
It was forged by Yasutsuna, a Hōki smith of the late Heian period, and bears his two-character signature. Its name, «the child-cutter», comes from the legend of Minamoto no Yorimitsu, who is said to have slain the demon Shuten Dōji with it on Mount Ōe. It passed through the Ashikaga, Toyotomi and Tokugawa houses and then to the Matsudaira of Tsuyama; it was designated a National Treasure in 1951 and is kept today at the Tokyo National Museum. It is a tachi with deep koshizori, an itame jigane and a nie ko-midare hamon.