A Miko (巫女) is a shrine maiden at a Shinto shrine. Miko were once considered to be something like oracles, in that they were said to relay the words of the gods during trances. However, modern day Miko are considered more like shrine attendants than oracles; it is often their job to keep a shrine clean and to sell charms as well as to aid Shinto priests during certain ceremonies. Miko also dance special ceremonial dances, known as miko-mai (巫女舞い), and offer fortune telling or omikuji (お神籤). They must be unmarried virgins; however, if they wish, they can marry and become priestesses themselves. Miko are often younger relatives of Shinto priests, such as daughters or granddaughters.
In Sailor Moon, Rei Hino was a Miko at her grandfather's shrine, and in the course of her duties, was able to use several powers that the other Sailor Senshi did not possess. She had ESP (extra sensory power) which manifested itself in her being able to sense things intuitively, through fire reading abilities, and also in precognative dreams. She could also use ofuda to immobilize her enemies with the chant 'Rin, pyou, tou, sha, kai, jin, retsu, zai, zen... Akuryo Taisan!' (臨、兵、闘、者、皆、陣、列、在、前... 悪霊退散！; "all warriors have been lined up in formation here... evil spirit begone!," an exorcising chant originated in China) even when she was not transformed.
In the anime, Rei treated her role as a Miko as somewhat of a part-time job, and not as something she wished to pursue as a career. Instead, she dreamt of several other careers, such as an anime seiyū or a globe-trotting career woman. In the manga and live-action series, Rei did consider her role as a Miko as lifelong, or at least until she decided to become a priestess in her own right.