The Priestess (Miko, 巫女) is a maiden who is brought into the Universe of the Four Gods from another world to summon a beast god in an assigned kingdom. Only virgin maidens can fulfill the role of a priestess. By gathering all of her celestial warriors, she is able to summon her corresponding beast god and is rewarded with the ability to grant three wishes after completing the summoning ceremony.
Ultimately, however, the priestess is a sacrifice to the beast god after she has coupled with him. As she summons the God, her body begins to mutate painfully (both Yui and Takiko experienced pain and scales that grew on their skins) and at the end of the summoning session, she will disappear.
Only Priestesses with a strong enough will survive the ordeal, if not, they are devoured by the god. Once all the wishes have been granted and the god summoned if the priestess survives she must return to her own world, as her mission is over and she cannot remain in the book.
False priestesses are young women from either the world of the book or the real one who take the place of a real priestess for one or another motive. Two of these fake Priestesses are Mayo Sakaki (tricked into becoming a false Priestess of Suzaku by a fake God) and Neiran (willingly usurped the Priestess of Byakko spot to improve her life, which had been terrible until then).
Yui Hongo was forced to become the Priestess of Genbu by Tomo (whose spirit was inhabiting a nameless vessel), who controlled her through the earring Nakago left her in order to steal the book. Tomo took his orders from Tenkou who planned to have Yui summon Genbu to break up the 100-year cycle of priestesses. This would have essentially erased Takiko Okuda's priestesshood and given Tenkou easy-access to the four gods' powers through however many priestesses he can summon into the book and manipulate.
Mariko Kobayashi, the protagonist of the Kagami no Miko game, a normal girl who's accidentally spirited into Hokkan and then becomes a companion of the Genbu Priestess Takiko Okuda. were in serious risk of being forced into becoming either a Priestess for another God other than the one she summons (Yui) or into a Priestess for a potential new one (Mariko).
Last but not least, Madoka Ootori and Misaki Himuro are the Priestesses of Suzuku and Seiryuu respectively in the video game Suzaku Ibun, where they replace (but also strongly resemble) Miaka and Yui.
- Mariko Kobayashi - potential Priestess for a new God (Kouryuu aka the Yellow Dragon) in Kagami no Miko.
These are the known special abilities displayed by the priestesses throughout their adventures:
- Communication Outside of The Book: While this ability is not exclusive to the priestess in dire situations, it is mainly the priestess who is able to hear whatever is going on outside of the book. As long as she and the reader of the book share a sort of item, she can hear whatever it is the reader is saying.
- Qi/Chi/Ki Barrier: Whenever a priestess is in grave danger, if her qi (energy) is strong enough, her beast god can siphon some if its powers onto her in the form of an energy shield. This is a rare occurrence and does not protect the priestess from other qi related attacks. Miaka is shown to be the only priestess (thus far) to manifest this ability.
- Color Glow/Light: The priestess has the ability to give off a kind of glow during times of danger or great stress. This glow not only confirms that she is the priestess but also allows her to travel out of the book if she has not remained inside of it for too long. And their light also based on what beast god they are summoning.
- Red Light - Priestess of Suzaku (Suzaku no Miko)
- Blue Light - Priestess of Seiryuu (Seiryuu no Miko)
- Silver Light (manga) - Priestess of Genbu (Genbu no Miko)
- Green Light (FY OVA 1 & FY OVA 2 intro) - Priestess of Genbu (Genbu no Miko)
- ? Light - Priestess of Byakko (Byakko no Miko)
- Summoning the Gods: The Beast Gods (Suzaku, Seiryuu, Genbu, Byakko) have bestowed the gift of being able to summon one of them onto the priestesses. Once the summoning ceremony is complete, the priestess is able to grant three wishes.