A shintai or goshintai ('go' is an honorific prefix) means the body of a kami (deity) in the Shinto religion.
A shintai also refers to a kamishiro as 'the world' in the Shintoistic view of the world, a kannabi (the place such as a mountain or a forest where the divine soul resides) in the Ancient Shinto, a jingi (sacred treasure) in the Imperial Household Shinto, a shinden (the main building of the shrine) since ancient times, a yashiro (shrine building) in the Shrine Shinto, and the place or object where the shimenawa ropes (sacred straw ropes) are stretched around as well. That is, a shintai means the place or object where the god resides or descends, (was enshrined, lives in secret, or exists) and also known as a mitamashiro (spirit replacement) or a yorishiro (object representative of a divine spirit, object to which a spirit is drawn or summoned, object or animal occupied by a kami).
Basically all the sects of Shinto have originated from the Ancient Shinto, and include the folk beliefs that other religions syncretized, the Shrine Shinto, and the Imperial Household Shinto. Each of them has its own characteristic shintai, and each characteristic deity is worshiped. The kami in the Ancient Shinto include yori-gami god (the god that comes from another distant world beyond the sea) and tsukumo-gami god (the divine spirit that lives in an extremely old tool or creature). Shrine Shinto and Imperial Household Shinto mainly humanized divinities (such divinities are sometimes referred to as "mikoto"). As a result, the Ancient Shinto is more comprehensive and subsumptive than the Shrine Shinto and the Imperial Household Shinto. The divinities are called in many ways such as kami (god), mikoto using the letters 尊 or 命, tama (soul), shoryo or mitama (both mean the departed soul), and have different meanings. Historically all these divinities have been subsumed and accepted without being defined in the Shinto religion, and thus everything in the universe can be a shintai, a mitamashiro, or a yorishiro.
A shintai is sometimes called kamiyo or kamishiro using the same letters 神代. A kamishiro is a container or dwelling of the god, which means the each deity's place or residence, and is used in contrast to the whole world called kamiyo (literally the world of gods) that includes utushiyo (this world) and tokoyo (the eternal, forever unchanging distant land over the sea, or the world of the dead, heaven). In this sense, a kamishiro is not a substitute container, but can be considered as the world of Shinto itself or the deity itself.
Temporary, simplified shintais
Some of the shintais are inherited for many generations; other shintais are renewed regularly. That is, the shintais can be divided into two categories: the first group of shintais is used for a regular period and then replaced by a new one, and the second group of shintais does not have a fixed period for use and replacement. Shintais that are updated include a gohei (ritual wand with pleated paper), a mikoshi (portable shrine carried in festivals), the onbashira (huge pillars of fir tree) of Suwa Grand Shrine, the shinden of Izumo Grand Shrine, and a yashiro as the shinden of ordinary shrines. How and when a shintai is renewed or taken over do not depend on its complexity or size. Specifically, well known shintais are: a gohei that are used for the Shinto rituals at mitamashiro-jinja shrines, a leafy branch represented by that of broad-leaved evergreen 'sakaki' tree as the simplified himorogi (primitive shrine, originally a piece of sacred land surrounded by evergreens; later a decorated sakaki branch on an eight-legged table), and a 'mikoshi' and a 'dashi (float)' in festivals.
the Ancient Shinto
In the Ancient Shinto, special, prominent sites (landmarks) such as the sea, river, mountain, forest, tree or rock were treated as the himorogi or iwakura (the place where a quieted god dwells) and were thought to be the shiniki (literally the sacred area, or Shinto shrine precincts), the place where a kami dwells, or the shintai. In other cases, the place where a kami stays (a shintai) was thought to be the boundary between this world and the eternal world and thus the entrance to the kingdom of gods. Furthermore, natural phenomena such as the Sun (sometimes called ohisama as its honorific), the fire, the volcano, the water (rain), the wind, and the lightning were, and are even now, worshiped.
The sacred tree or the meotoiwa (a pair of rocks in two sizes, the larger one is thought to be the husband, the smaller the wife) in the himorogi belief and the iwakura belief in the Ancient Shinto, and Mt. Fuji as a sacred mountain are also called a kannabi which means the place or object where a quieted god always dwells or secretly lives (stays) in utshushiyo. In addition, the places where the shimenawa ropes are stretched around include a rice paddy struck by a thunderbolt (lightning).
The Imperial Shinto
The mitamashiro (spirit replacement) of a high-ranking kami was also thought to be a shintai. The shintais of the mikoto (humanized divinity with a human figure and heart) in Japanese mythology are also called 'Three Sacred Treasures' which mean a mirror, a sword, and a comma-shaped jewel, and are thought to be the artificial mitamashiro of the highest rank. The Imperial Household Shinto has something to do with this, and the Imperial Household is said to own the Three Sacred Treasures.
Originally the grand sumo tournament was a Shinto ritual dedicated to the Imperial family in the Imperial Household Shinto. As a result, among the ozeki wrestlers, the highest ranking sumo wrestlers, only the chosen ones can wear the yokozuna, a shimenawa rope, as the proof of the shintai of a kami.
The Shrine Shinto
At the yashiro of a shrine the shimenawa ropes are stretched as the proof of the shintai. Most of the shrines of the Shrine Shinto were originally constructed at the site of himorogi or iwakura. Shrines with a long history often do not have a main shrine building, and the hill or the sacred tree can be the goshintai (Suwa-jinja Shrine). In areas with strong folk beliefs to help having babies, a phallic symbol can be a shintai for fertility. Also a 'yashiro' has existed since ancient times in the Shrine Shinto; ruins of shrine buildings that were used for festivals and rituals have been excavated from the sites.