The Shitennō are Buddhist protectors of the four directions. They ward off evil, guard the nation, and protect the world from malicious spirits, hence the Japanese term Gose Shitennō 護世四天王, literally “four world-protecting deva kings.” Each represents a direction, season, color, virtue, and element . They originated in India as deva generals protecting Lord Indra, but were later adopted into the Buddhist pantheon in China and Japan.
Each dwells in and protects one of the four continents surrounding Mt. Shumisen 須弥山 (Skt. = Mt. Sumeru), the mythical home of the Historical Buddha and other Buddhist deities. In China and Japan, they are venerated as temple guardians and protectors of the nation. In China, statues of the four are often placed near temple entrances, but in Japan, effigies of the four are more commonly placed around the central deity on the main altar (the main dais is befittingly called the Shumidan 須弥壇). The four are commanded by Taishakuten (Skt. Indra), Lord of the Center.
They are nearly always dressed in armor (yoroi 鎧), looking ferocious (funnusō 忿怒相), and carrying weapons or objects (jimotsu 持物) said to eliminate evil influences and suppress the enemies of Buddhism. They are also typically shown standing atop evil spirits (known as Jaki in Japan), symbolizing their power to repel and defeat evil. Sometimes they are depicted with a fiery halo behind them. Their attributes, however, are not rigidly prescribed and thus differ among Buddhist nations. Shitennō iconography is related to the Four Celestial Emblems (dragon, red bird, tiger, turtle) of China, who also guard the four cardinal directions.
In Japanese statuary, the Shitennō are almost always portrayed in animated warrior poses rather than static postures of ease or meditation. Among the four, Tamonten (aka Bishamonten) is considered the most powerful, and over time, supplanted the other three in importance. Indeed, Bishamonten is the only member of the four worshipped independently in Japan, both as protector of Buddhist faith and as one of Japan’s Seven Lucky Gods -- one who brings wealth and prosperity. Bishamonten also supplanted Taishakuten (Lord of the Center) as an object of worship, but Taishakuten never enjoyed great status in Japan.
The four appear in numerous scriptures, including the the Goldern Light Sutra 金光明經 (Konkōmyō kyō). Translated by Dharmakṣema 曇無讖 in the early 5th century, by Baogui 寶貴 in the late 6th century, and by Chinese monk Yijing 義淨 (635-713), it teaches that rulers who worship this sutra will gain the protection of the four guardian kings 護四王 in safeguarding the nation and benefiting its people. The Golden Light Sutra, also known as the Konkōmyō saishō ō kyō 金光明最勝王経, was one of three texts of great influence in old Japan for protecting the nation -- the so-called "three scriptures for protecting the state" are the Golden Light Sutra, the Lotus Sutra 法華經 (Hokke kyō), and the Benevolent Kings Sutra 仁王經 (Nin ō gyō). In the popular Lotus Sutra -- translated into Chinese by Kumārajīva 鳩摩羅什 350 - 410 (Jp. = Kumarajū) -- they appear in the Dharani (26th chapter), with Jikokuten and Tamonten pledging on behalf of all four to protect those who embrace the sutra’s teachings.
The four Shitennō guardians were transmitted from India to China and elsewhere in Asia around the 6th century AD. One of the earliest representations of the four in China, dated to the late 6th century, is from the Dunhaung Caves (cave 428). Another early example is a gigantic stone statue of Tamonten located at the Longmen Grottoes (Fengxian Temple 奉先寺) in China, completed circa 672-675 AD.
The four were introduced to Japan at least by the late 6th century, for Shōtoku Taishi (the first royal patron of Buddhism in Japan) commissioned the construction of Shitennōji Temple 四天王寺 in Osaka in 593 AD to venerate the four. According to the Nihongi 日本紀 (Chronicles of Japan; compiled around +720), Shōtoku had prayed to the four to help him defeat Mononobe no Moriya 物部守屋 (died 587) and other forces opposed to the introduction of Buddhism in Japan.
Shōtoku achieved victory, and built Shitennōji Temple soon thereafter. Because of their early introduction to Japan, the four are widely disseminated throughout the Japanese islands -- nearly every major temple in every major region has its own set of the four. The four also appear often in the mandala paintings of Japan’s Esoteric Buddhist sects, but their functions and symbolism were largely supplanted from the 9th century onward by esoteric groupings such as the Five Tathagata (with Dainichi Nyorai in the center), Five Great Mantra Kings (with Fudō Myō-ō in the center), and the 12 Deva (guardians of the 12 directions). Outstanding extant sculptural sets of the four Shitennō can be found at:
Guardians of the Four Directions, Protectors of Buddhist Law, Protectors of Human Kind, Protectors of the Bosatsu and Nyorai. Most often found standing at the corners of alters. Ferocious looking, sometimes with fiery halo behind them, often stepping on demons called Jyaki. They protect the Buddhist realm for Taishakuten (Skt. Indra), serving as his generals to guard the territories inhabited by humans. Originally from Hindu mythology, and later incorporated into Buddhism.
In the Lotus Sutra, they vow to protect those who believe in the Dharma (Buddhist teachings). In Japanese artwork, especially in the mandala form, the four typically appear in a set order, starting with Jikokuten (East), followed by Zōchōten (South), Kōmokuten (West), and Tamonten (North). All four are described in Sanskrit, Chinese and Japanese texts, but their attributes, colors, and names often vary.