The Jade Court of Vampires….this sect has in fact yet to make an appearance in the Series. However, the appearance of this court is eminent, and should they fail to make an appearance, will leave this Reader quite disgruntled.
On a purely speculative note:
It's possible that the Jade Court is comprised of Jiang Shi, or "Chinese Vampires."
In mythology, Jiang Shi are thought to be reanimated corpses that kill living creatures to absorb life essence from their victims. They are also known for their greenish-white furry skin, perhaps derived from fungus or mould growing on their corpses/bodies. Again, this is purely speculative; based on some knowledge of Asian mythology, Shiro saying that they stay in the East, and way too much free time left thinking about this series.