A komainu ("石獅子" in Chinese and "imperial guardian lion" in English) is an imaginary mythical beast that resembles a dog and lion mixed together. Komainu are placed in pairs, one of each on either side of the entrance to a shrine or temple or the façade of its main hall. Strictly speaking, these should be referred to as "Shishi komainu" (literally, "lion dogs").
Origin of its name
According to some scholars, its name suggests that Komainu is a dog from Koma (Goryeo). This is because they are considered to have come through Korea. But the leading theory is that Komainu has an Indian origin. In the first place, there is no cultural history of Komainu in Korea, and the Chinese character, "高麗", has been used just to borrow the sound; Komainu was never meant to be a dog from Korea, but was thought to be an imaginary divine beast, and Shishi, the other in pairs, is a lion, which had never been witnessed by the Japanese at that time. This leads us to conclude that the Shishi is not a lion, but a mythical divine beast named "Shishi".
Typically, the statue on your right is an Agyo, which has no horns and has its mouth open. The statue on your left is Ungyo, which has one horn, with its mouth closed. We often call them both "Komainu" without distinguishing them from each other, but more strictly speaking, they should be called "Shishi/komainu" as the statue without any horns is called "Shishi" and the other with a horn "Komainu". The Komainu statues, created from the Showa era onwards, do not have a horn no matter on which side they are placed. These should be primarily called "Shishi".
Komainu in shrines and temples
Although Komainu seen on the grounds of temples or shrines are often made of stone or bronze, some placed inside the main shrine are made of wood.
According to a description of Saemonfu of the Left and Right (the offices that safeguarded palace gates) in Volume 46 of Engishiki jinmyocho (a list of shrines), Komainu were placed on the left side of the Kaiin-mon gate on a Taigibi day (a day of an imperial ceremony) and returned to Saemonfu when the ceremony was over. This also suggests that Emonfu of the Right placed the statue on the right side of the gate; all of these signify that the Komainu dates back to the Heian era. Among the Shishi/komainu statues of that time, the ones in the Chinju Hachimangu shrine of the Yakushi-ji temple in Nara are well-known; they are made of wood and have been designated important cultural assets. However, as neither of the statues have a horn, they should be more appropriately called "Shishi pair". Other Komainu statues that have been designated important cultural assets include those of the Daiho Jinja shrine in Shiga, the Kozan-ji temple in Kyoto, and the Itsukushima Jinja shrine in Hiroshima.
Although similar statues are found in China and Korea, those that come in a pair of A-un (Agyo and Ungyo) are typically seen in Japan. This may be because they were under the influence of Kongo rikishi (a guardian deity of Buddhism) and the A-un style had already become the norm by the end of the Heian era. However, from modern to the present age in Japan, the vast number of Komainu have been made in various forms and shapes. For example, the statues of other animals like boars, dragons, or foxes, play a similar role as well. In Shinto, all of these animals are called Shinshi (the messengers of the god). Many shrines (or enshrined gods) have adopted specific animals as their Shinshi. Most notable are foxes in the Inari-jinja shrine, deer in the Kasuga-jinja shrine, and snakes in Benzaiten. Some are based on local lore. For example, at the Joken-ji temple in Tono, the statues of kappa (a legendary creature, assumed to carry a dish filled with water on its head) are standing where Komainu are supposed to be, following the local legend of the kappa.
They are typically placed with their backs against the temples or shrines that they are supposed to protect. In some exceptions, however, some are placed facing towards the temples or shrines. Some do not come in pairs although they are few in number.
Komainu as a couple
Some temples or shrines consider Komainu on your right and your left as a couple. As long as Komainu are in the shape of Shishi (liondog), the one that has mane is no doubt male. Some insist that the above view is wrong as it is biologicallyimpossible for two Komainu to make a couple. On the other hand, some support the view that they are a couple as some breast-feed or pacify their Komainu or Shishi puppies. There is no use arguing over which is right, but the fact is that there are two theories; one is to support the view that a pair of Komainu is a couple and the other is to oppose to it.
Imaginary beasts other than Komainu