Transformation: Adamantine Staff

The user transforms into a staff. The staff is as hard as diamond, making it very destructive. This also renders it largely impervious to damage, making it useful as a defence; despite this, the user still feels pain as seen from Enma clashing with the Sword of Kusanagi. The staff is also able to extend to great lengths, enough that, in the anime, it could push the Nine-Tails beyond the borders of Konohagakure. The user can produce any part of his regular body from the staff, such as his claws or fangs, to surprise opponents.

Trivia

 * Fighting alongside Monkey King: Enma, this was the preferred weapon of Hiruzen Sarutobi; Hiruzen has wielded the staff through decades of warfare, contributing to his reputation as a "God of Shinobi
 * The folkloric Sun Wukong had an extendable staff called Ruyi Jingu Bang (read in Japanese on'yomi as the "Nyoi Kinko Bō"). As in the story, Enma's transformation has golden-shaft ends.
 * A nyoi, which can be translated as priest's staff but literally means as one wishes, is an decorative object associated with Chinese Buddhist rituals.
 * is a weapon used as a ritual object to symbolise both the properties of a diamond (indestructibility) and a thunderbolt (irresistible force). In Japanese, the term is also synonymous with adamantine.
 * This also references Sun Wukong's staff, which had to be made heavy and durable in order for Wukong to be able to use it (due to other weapons being wielded by him ending up broken).