Shijin-so-o Topography (四神相応)
The term "Shijin-so-o" refers to the topography and land physiognomy that are traditionally believed to be the best suited for the 'Four Gods' that govern the four directions of the heavens in China, Korea and Japan. It is also called Shichi-so-o topography. The Four Gods with an 'Oryu' (yellow dragon) or Kirin at their center are called the 'Go-jin' (Five Gods). However, the correspondence between the Four Gods and actual geography in Japan differs greatly from that in China, South Korea, and North Korea.
China and Korea
Shijin-so-o topography in the feng shui of China and Korea indicates the form of Zofujusui (storing wind and collecting water) in which the terrain is enclosed by having tall mountains at the back (Haizan-Rinsui), a lake, river, or sea in the front (Sui), and smaller hills or mountains (Sa) on both sides. The Four Gods in this case are as follows: the mountains in the back are Genbu (black warrior); Sui in front is Suzaku (a red phoenix); the left Sa with Genbu in the background is Seiryu (a blue dragon) and the right Sa is Byakko (a white tiger).
In Kyoto, Japan it was possible to have the following association: the Tanzawa Mountains in the north as Genbu, Mt. Hidari-Daimonji as Seiryusa, Arashiyama in the west as Byakkosa and Ogura-ike Pond in the south as Suzaku; therefore, Kyoto was a land of Shijin-so-o topography exactly from the perspective of the feng shui standard. However, Ogura-ike Pond was completely consumed by landfills, which broke the Shijin-so-o topography of Kyoto. Mt. Funaoka, which once overlooked Suzaku-oji Avenue, is a little too small for Genbu. In the standard viewpoint of feng shui, Mt. Funaoka is interpreted as Seiho, to which Sanryu, a dragon of mountains, is headed via Genbu.
Japan
In modern Japan, the interpretation that the Four Gods are related to 'mountain, river, road and lake,' as shown in the following table, is generally accepted. However, this association has not necessarily been settled since ancient times.
The "Sakuteiki Gardening Book" is source of the theory that equates the Four Gods to 'mountain, river, road and lake.'
"Sakuteiki Gardening Book" explains how to create a garden, taking Shinden-zukuri (a style of architecture for the residence of court nobles) into consideration, in which the theory of 'Four Gods = Mountain, river, road and lake' is described as the ideal basis for such a garden. It also explains that planting certain kinds of trees can substitute 'The Four Gods = Mountain, river, road and lake' in the event there is no mountain, river, road and lake to represent the Four Gods.
The interpretation that the Four Gods are related to 'mountain, river, road and lake' has been generally accepted in modern Japan, since the association of Seiryu=Kamo-gawa River (the Yodo-gawa River system), Byakko=Sanin-do Road, Suzaku=Ogura-ike Pond and Genbu=Mt. Funaoka was relatively successful with Heian-kyo as a model.
In fact, "Sakuteiki Gardening Book" mentions nothing about Heian-kyo, much less the specific places of the mountain, river, road and lake. It is said that "Sakuteiki Gardening Book" was created at the end of the Heian period, judging by its content, which is why the theory of 'Four Gods = Mountain, river, road and lake' can only date back to the end of the Heian period. Therefore, we need to pay attention to the fact that there is no proof of the argument based on the assumption that this theory is the ideological background for choosing the land for Heian-kyo, which was built in the late eighth century. Moreover, the association of mountain, river, road and lake, as allegedly done well into the Heian-kyo, has been claimed since the Edo period, which became the general interpretation later in the Meiji period.
In fact, even though a city prior to the Edo period would have been designed to match the Shijin-so-o topography, it is very unlikely that the Four Gods were Mountain, River, Road and Lake.
For example, in the imperial rescript, when building the capital, Heijo-kyo is described as follows:
Right now, the place of Heijo is in accordance with the painting of four beasts; three mountains assuage things, and turtle augury tells the same.'
The phrase 'accordance with the painting of four beasts' here means Shijin-so-o topography, which confirms that during the Nara period Heijo-kyo was considered to be the place having Shijin-so-o topography. The location of Heijo-kyo doesn't apply to a mountain, river, road and lake as described for Heian-kyo. However, as long as it is associated with Shijin-so-o topography it is likely that another interpretation would have been accepted during the Nara period.
Shirin Saiyo-sho commentary in the late Kamakura period mentions that 'the central mountains are related to Genbu, and the people, panoply and oven are related to Suzaku...,' which shows that Suzaku was associated with 'people, panoply and oven.'
Moreover, "Ryueihikan" mentions that 'Winds of the Edo Castle merit the position of the world's castle, and its land coincides with Shijin-so-o topography'. The author of "Ryueihikan", Yamon KIKUCHI, considered that Edo Castle was built on the land coinciding with Shijin-so-o topography. But if applying the theory that 'Four Gods = Mountain, river, road and lake', then Tokyo Bay, which is likely to be Suzaku (god said to rule over the southern heavens), spreads from east to south-by-southeast, and Koshu-kaido Road, which is likely to be Byakko (god said to rule over the western heavens), only stretches to the west no matter how you see them in their favor."
It is far-fetched to say that such geography matches the theory of 'Four Gods = Mountain, river, road and lake.'
Furthermore, the interpretation that Himeji Castle, Fukuyama Castle (Bingo-no-kuni) or Kumamoto Castle matches the Shijin-so-o topography of 'Mountain, river, road and lake' theory emerged later.
As for Nagoya Castle, "Kinjo-onko-roku records" mentions that 'Your great castle has roads open to four directions, and people gather from all over the world; like the world's castle, it places chokepoints at about 40 kilometers; it has mountains in the east, the sea in the south, Kiso-gawa River in the northwest, and in between it installs strategic stops at a distance of about 140 kilometers (omission); lying ahead, a fort on Mt. Yagoto in the east, Saya and the armed camp in Kiyosu in the west (omission); with the castle, camps and walls, these indicate the key castle of Shijin-so-o topography.'
The Shijin-so-o topography described in "Kinjo-onko-roku records" is not 'mountain, river, road and lake,' either.
There is no concept of certain fortune on a certain direction in the feng shui of ancient China, so it is an original Japanese concept to abhor Kimon (the direction of northeast, called an ogre gate) and Urakimon (the direction of southwest which is the opposite side of Kimon). In this sense, one must doubt the theory expressed in "Kamadoyama Kyuki histroy book" that Dazaifu Tenmangu Shrine was made based on feng shui according to the description that Kamado-jinja Shrine was made to protect Kimon of Dazaifu Tenmangu Shrine at the time of its construction.
This is how the interpretation of Shijin-so-o topography has changed from ancient times to the early modern times, and it is believed to be unique and different from the feng shui of ancient China.
Examples of Shijin-so-o Topography in Modern Times
Grand Sumo - The four tassels with different colors above the sumo ring were relics of four pillars that originally held up the roof of Kataya, indicating the Four Gods.