We know the Shitennō as the four generals of the Dark Kingdom – Jedeite, Nephrite, Zoicite and Kunzite. However, this title has a deeper meaning in the Japanese culture. First, let’s take a look at the kanji that forms the word “Shitennō”: 四天王. 四 (shi) is the number 4, 天 (ten) refers to something heavenly and 王 (ou) means “king”. So the best translation for this title is “The Four Heavenly Kings”.
I looked into it, and turns out that the Shitennō (or “The Four Heavenly Kings”), are actually four guardian gods which emerged form the Buddhist religion. They originated in India as the “Celestial Generals” who protect Lord Indra, and were later adopted into the Buddhism of China and Japan. Their names in Japanese are: Tamon-ten, Zōchō-ten, Jikoku-ten and Kōmoku-ten.
Each deity was associated with a direction, color, gemstone, element, season, planet, animal, internal organ etc. Tamon-ten (or Bishamon-ten), King of the North, was related to winter, the element earth and the color black. Zōchō-ten, King of the South, is related to summer, fire and the color red. Jikoku-ten, King of the East, represents spring, water, and green/blue (both colors are called ‘Ao’ in Japanese). Kōmoku-ten, King of the West, represents fall, metal and the color white.
The Shitennō were also related to the four mythological creatures of the Chinese star-constellations, who also guard the four directions (yes, Fushigi Yuugi fans, these are the very same gods): the Vermilion Bird of the South (Suzaku), the Black Tortoise of the North (Genbu), the Azure Dragon of the East (Seiryū) and the White Tiger of the West (Biakko).
According to the legend, each of these gods watches over and protects one cardinal direction of the world. In the Sailor Moon manga, each one of the generals is in charge of a different division of the Dark Kingdom, as well as searching for the Ginzuishou on a different continent (different parts of the world). Jedeite commands the Far-Eastern division, Nephrite commends the North-American division, Zoicite commends the European division and Kunzite commends the Middle-Eastern division.
In the Japanese history, this title also applies to loyal retainers in groups of four, to certain of Japan’s most famous legendary and historical characters. For example, the four samurai who were the protectors of shogun Minamoto Yorimitsu were also titled as Shitennō.
Since the Shitennō are protectors, they are icongoraphed as warriors. They are sometimes referred to as generals and always hold some sort of a weapon. In the manga, the generals of the Dark Kingdom originally served as protectors of their lord – Prince Endymion. But unlike the mythical Shitennō, these general eventually turned to the dark side.
With all the resemblance of the Dark Kingdom generals to the mythical deities, I’m positively sure that each general represents one of the deities. However, I’m still not sure which is which ^^;;.