Urusai

Urusai, 'noisy', was a jade katana. In the Isawa Mori a Mujina tricked several earth kami into a tree and then sealed them with their most prized possesion, Urusai. The blade lay buried there until 1123, when a group of magistrates release the blade from the earth, freeing the kami. In gratitude they gave the sword to the group. Urusai was used to defeat Kuzushi no Oni and his minions inside the Mori Kuroi, the 'Black Forest'.