The torii represents a dividing line (kekkai) between sacred and secular areas, serving as an entrance to the sacred world in Shinto shrines and other holy places. It's a kind of gate. Although some torii have been built at imperial tombs and Buddhist temples, a torii is typically a symbol of Shinto shrines and a symbol representing a gate is used on maps to identify shrines.
There are several theories about the origin of torii, but none of them is clear. They may have originated from the practice of placing bird perches before an altar that is associated with the Tokoyo no naganakidori (roosters) that were made to crow so as to draw Amaterasu Omikami (a female Shinto deity) out of Ama no iwato (literally, "the rock cave of heaven"), but other scholars suggest that they have foreign origins, believing that they may be related to one of the following: the torana (gate) of Indian Buddhism; the kahyo (a type of ceromonial column called "huabiao" in Chinese), torizao (a type of bird-catching pole), or pailo (a piece of architecture shaped like an archway) of China; the kozenmon (a red gate) of the Korean Peninsula; or the portable temples of Israel. In any event, by the eighth century they had obtained the shape we now recognize.
Likewise, the origin of the word remains uncertain. There are several theories: the word may have originated from '鶏居' (bird perch), from "toori-iru (pass through and enter)" or from the way it had been pronounced ("Torana"), to which Chinese characters were applied.
How to count torii
Torii are counted as i-ki (one ki of torii) and ni-ki (two ki of torii). When there is more than one torii in the approach, we call the first of the torii "ichi no torii' and the second of the torii "ni no torii," starting with the one farthest from the shrine.
The torii's basic structure has two columns topped with horizontal rails respectively called the kasagi and shimagi, and below the top two rails is another horizontal rail called the nuki, which connects the two columns.
Torii are generally classified into two styles--the shinmei style and myojin style--from which various derivatives have been developed. The type of torii to be built is a matter of choice by the donor and has little bearing on the god worshipped in the shrine, as shown in Kashima Jingu Shrine, where a Kasuga-style torii is built; however, some torii (like Sanno-style torii) are associated with Hie Jinja Shrine (Sanno Jinja Shrine and Hiyoshi Jinja Shrine).
A shinmei-style torii, when considered as a whole, has a fundamentally linear design. Boards are used for the kasagi and nuki. This type of torii does not have the shimagi below the kasagi; instead, its columns consist of unsquared logs, which are vertically erected. As a derivative of this type, torii that use a square log for the nuki are so commonly seen in gokoku jinja shrines (shrines designated as places of worship for people killed in the war), including Yasukuni Jinja Shrine, that they are distinguished from the rest and called Yasukuni torii.
The Myojin-style torii, seen as a whole, has a decorative curvilinear design. The shimagi is placed below the kasagi, and the columns are slightly tilted.
The Inari-style torii is also referred to as the Dairin-style torii. It is known for its vermilion color.
Torii are made of wood (cedar or cypress) or stone. Torii that are fully covered in copper sheets are called Karakane no torii and were depicted in the ukiyoe (woodblock prints) of the Edo period. In recent years, some torii have contained iron pulp or have been made of reinforced concrete.
Other torii made of unusual materials include the torii of Sueyama Jinja Shrine in Arita-cho, Nishimatsuura District, Saga Prefecture (made of porcelain); that of Hiko Jinja Shrine in Yawata City, Kyoto Prefecture (made of duralumin), and that of Soegawa Jinja Shrine in Hachirogata-cho, Akita Prefecture (made of chloroethene).
Three Famous Torii in Japan
Kane no torii (bronze torii) of Yoshino (designated as an important cultural asset)
Standing on the approach to Zao-do of Kinpusen-ji Temple
Considered to be built during the Muromachi period
Eight meters tall
Its gakuzuka (a frame hung between the shimagi and the nuki) says "Hosshinmon."
Miyajima of Aki / Shutan no odorii (Great red torii) (made of wood) (designated as an important cultural asset and a world heritage)
It stands out in the sea before the temple of Itsukushima Jinja Shrine.
A Ryobu-style torii made of Japanese cinnamon
The current torii, completed in July 1875, is the eighth-generation torii as counted from the first one, which was built during the Heian period.
Shingaku (a frame hung in front of the torii, carrying the name of the shrine): on the sea side: ’厳島神社' (Itsukushima Jinja Shrine) / on the shrine side: ’伊都岐島神社' (Itsukushima Jinja Shrine) (written by Prince Arisugawa Taruhito)
Ishi no torii (stone torii) of Osaka Shitenno-ji Temple (designated as an important cultural asset)
Built in 1294, it is considered to be one of the oldest large stone torii in Japan.
Its hengaku (framed statement) reads, "This is the place where Buddha appeared and gave lectures to people, and is the east gate to Paradise."
There are 10,000 torii in this shrine.
Heian Jingu Shrine
It has one of Japan's largest torii, standing 24.4 meters tall.
Izumo Taisha Shrine
Its torii was built by Tokuichiro KOBAYASHI (Kokura, Kitakyushu City), a well-known devotee of dedications.
Hike Jingu Shrine
Designated as an important cultural asset
The third-highest wooden torii
Motoki no ishi torii (Stone torii of Motoki)
Designated as an important cultural asset
The oldest stone torii in Yamagata Prefecture, it was built in the Heian period.
Other examples where the torii gate mark is typically used include the map and a sign for banning urination and the unlawful dumping of garbage.
Popular beliefs concerning torii
It is commonly believed that if one can throw a stone onto the top of the torii, one's wish will be granted.
A measure against the unlawful dumping of garbage
Nowadays, we see torii as small as 10 to 50 centimeters high placed in residential or vacant areas. The simplest torii is the one made of a thin board that is cut in the shape of a torii and attached to a concrete or block fence, which might also have one drawn on it in red paint. These small torii were set up to prevent the unlawful dumping of garbage, taking advantage of the innate human reverence for it as an entrance to the sacred world, and there have been real-world examples in which dumping has dramatically decreased. Additionally, note that in response to those who say it is a shame to imitate a real torii for this type of purpose, an unusual torii has been in use with the nuki (lower horizontal rail) being longer than the kasagi (upper horizontal rail), which is opposite that of the classical design. Because it was started when illegal dumping was not a problem, this may have originated in an attempt to prevent people from urinating outside by drawing the shape of a torii in red paint at the bottom of a fence. In any event, this story most simply and adequately reveals the relationship between religion and morality.