Ghost Monkey - The Scrolls of Chaos and Order, #3

The Sankive Jungle is home to humans, elemental spirits, shapeshifters, and demons. Stories of demons are from long ago, but their serpentine descendants, the Fangs, haunt the jungle. With the war between the Jayan Empire and the Fangs reaching a peak, something dark and ancient rears its head. Sugriva, a shapeshifting macaque, is of the warrior caste. His unit is disposable, fighting on the front lines against corrupted serpent shifters.
However, he willingly strays from his caste often, and in doing so he meets powerful spirits...and forgotten demons. Will he survive? Or will he succumb to the corruption and become a demon himself? This is the tale of the Ghost Monkey of Sankive, the Feral Monkey who slaughtered a thousand demons.