Amurui

 is a mad bear Anima.

Traits
The Amurui Anima like other Anima gives the owner an animal ability, however unlike others it induces an uncontrollable state of rage.

It has been shown to transfer a part of itself into +Anima, thereby putting them into a state of madness also.

History
The Kim-un-kur considered Amurui roaming Moss Mountain to be a problem so they assembled a hunting party to eliminate it. Among the group were Riiya, Upas and Senri. During the hunt, Senri wandered off and was attacked by Amurui. Riiya tried to take Senri to safety while Upas fought Amurui. After Amurui overpowered Upas, Riiya came back to fight, but Amurui infected Riiya with the mad Anima. Riiya killed the bear Amurui, but now with the uncontrollable Anima inside of him, he turned on his own son Senri. Riiya transferred his own Anima to Senri who then killed him.

This was believed to be the last of Amurui, however a part of the Anima had been transferred to Senri, and also at some point prior to this the bear Amurui had a cub.

Plot
Throughout the series, Senri unknowingly has the Amurui Anima inside of him; the use of his eyepatch helps him keep the rage in check.

When Igneous Giesrieg undergoes his trial at Moss Mountain, he is attacked by the Amurui cub. Simultaneously, Upas challenges Senri to a fight, intent on killing him and the last of Amurui. During this fight, Senri loses control of the Amurui Anima. After hearing the cub's roar, Senri rushes over, fights it and kills it. Upas tries to start his fight with Senri again, but Husky is able to calm Senri down, which convinces Upas to let him live.