the Palace of the Setting Sun in Chang’an southern section. They can also appear in other building, as mentioned by Sharak Sanzo. They are like the Three Magi. Their real bodies are in heaven, and only their faces are projected as holograms onto the water screen in the temple's audience chamber.
From the right they represent three types of concepts such as “female, male, neuter” and “peace, neutrality, chaos”, and express corresponding views to Sanzo and the others.