One of the five most famous swords in Japanese history, forged nearly a thousand years ago by Aoe Tsunetsugu. It was presented to the famed monk Nichiren as a gift from a follower to celebrate his founding of Kuon-ji temple on Mt. Minobu in 1281.
Nichiren wound Buddhist prayer beads around its hilt to ward off evil. Some time after this, the temple's guardian goddess Shichimen Tennyo manifested and transformed into a red dragon. It is thought that she is the guardian spirit that inhabits this sword, making it a Living Weapon.