Korōshibyō

Korōshibyō (虎狼 死病, wild beasts fatal disease) is a Kekkei Genkai of the Mushinoiki family. It is a powerful Kekkei Genkai that "releases" a wild state in the user, and in the process awakening their animal instincts.

The Korōshibyō, stemming from Iwagakure was the original technique of the Mushinoiki family. Releasing their chakra, they would enter a beastly form and gain enhanced abilities. There senses, strength, speed, etc all increased to a point where they would loose their humanity. While in the newest generations and such, this is viewed as a powerful ability, the original clan members saw it as a curse. When in battle, they would un-willingly become a feral beast and loose control over their emotions. It wasn't until the Great Elder Chō, a prominent Mushinoiki family member found a way to subdue this "curse" to the hosts command.