What is Onmyōdō?
Abe no Seimei, shikigami, the Four Symbols and protection from evil

A historical onmyoji (court diviner) of the mid-Heian period recorded in official sources. Trained under the Kamo lineage in astronomy, calendrics, and divination, he performed purifications and ritual steps (heihaku/henbai) at court. Diaries note the trust he gained from Emperors Kazan and Ichijo and from Fujiwara no Michinaga. He later also held the post of Astronomer-in-Chief, paving the way for the Abe (Tsuchimikado) lineage to codify Onmyodo as a hereditary tradition. Over time his legend grew, and he came to embody the archetype of the sorcerer who subdues yokai and commands shikigami.

Seiryū, the Azure Dragon, is one of the Four Symbols (shijin) that guard the cardinal directions, the numinous beast that shapes the seven eastern lunar mansions of the heavens into the form of a dragon. In the Five Phases it is assigned to Wood, in the five colors to azure (blue-green), and in the seasons to spring; it embodies the direction east itself. Arising from Chinese astral belief, the Huainanzi's "Treatise on the Patterns of Heaven" makes the beast of the east the Azure Dragon, fully correlating it with the five directions, the Five Phases, and the Five Emperors. After it was transmitted to ancient Japan, it was absorbed into Onmyōdō and the geomantic reading of capital sites, and depicted as a marker of directional protection.

Byakko, the White Tiger, is one of the Four Symbols that guard the west, the divine beast that shapes the seven western lunar mansions of the heavens into the form of a tiger. In the Five Phases it is assigned to Metal, in the five colors to white, and in the seasons to autumn, and it is represented as a fierce white-furred tiger. Arising from Chinese astral and Five Phases thought, the Huainanzi's "Treatise on the Patterns of Heaven" makes the beast of the west the White Tiger. After it was received into ancient Japan, it formed a pair with the Azure Dragon and was depicted as a marker of directional protection and of wards.

Suzaku, the Vermilion Bird, is one of the Four Symbols that guard the south, the numinous bird that shapes the seven southern lunar mansions of the heavens into the form of a bird. In the Five Phases it is assigned to Fire, in the five colors to vermilion (red), and in the seasons to summer. In the classics it is often written "Vermilion Sparrow," and the "Qu Li" chapter of the Book of Rites makes the Four Symbols markers of direction—"the Vermilion Bird in front, the Black Tortoise behind." Received into ancient Japan together with the Chinese thought of direction and the Five Phases, its name remains in the Suzaku Avenue and Suzaku Gate of Heian-kyō.

Genbu, the Black Tortoise, is one of the Four Symbols that guard the north, the numinous beast that figures the seven northern lunar mansions of the heavens. It is often represented as a tortoise entwined with a snake (tortoise-and-snake intertwined), and is assigned to Water in the Five Phases, to dark (black) in the five colors, and to winter in the seasons. Arising from Chinese astral belief, the Huainanzi's "Treatise on the Patterns of Heaven" makes the beast of the north the Black Tortoise. After it was received into ancient Japan, it was spoken of together with the notion of "land matching the Four Symbols," which holds that terrain backed by a mountain to the rear—the "Genbu" position—is auspicious.

The Hōsōshi originated as the figure charged with driving away evil in China’s Great Nuo ceremony. In Japan, the Hōsōshi became the central performer in the court’s Ōna and tsuina rites, expelling spirits believed to cause epidemics. Early records describe a square, four-eyed mask symbolizing command of the four directions, a halberd in the right hand, a great shield in the left, and a bearskin costume. Accompanied by ritual attendants known as shinshi and nanin, the Hōsōshi processed through the imperial palace and drove pestilence beyond its gates. The ceremony eventually became part of the annual court calendar.

Ototen and Wakaten are two *Goho-doji* (Dharma-protecting youths) who are said to have constantly attended and protected Shoku Shonin (910–1007), the founder of Engyoji Temple on Mount Shosha in Harima Province. A *Goho-doji* is a fierce deity (*kishin*) in the form of a child who is subdued and commanded by highly virtuous ascetic practitioners of Shugendo or Esoteric Buddhism to protect them and carry out their will. Ototen and Wakaten are known as a representative pair of such beings. According to temple legend, Ototen is an incarnation of Fudo Myoo, and Wakaten is an incarnation of Bishamonten, and they attended Shoku Shonin on his left and right in the forms of a blue ogre and a red ogre, respectively. While Shoku undertook rigorous ascetic practices secluded deep in the mountains of Mount Shosha, they appeared like heavenly children to fetch firewood and water, repel external enemies, and were revered as beings embodying the holy man's spiritual power. Their nature is well expressed in their duality: despite being fierce ogre-deities, they submit to a holy monk and protect the Buddhist teachings—in other words, they are "ogres yet benevolent gods of Dharma protection."

Hakutaku is an auspicious beast from ancient Chinese lore said to understand human speech and to know all manner of monsters, demons, and calamities. It appears in eras of virtuous rulership, and the famed Hakutaku Chart records creatures of anomaly and methods to counter them. In Japan, such images spread in the Edo period as talismans against misfortune, carried for safe travel and protection from illness. Depictions show a white beast, with features varying by period.

Shōki is a demon-banishing deity originating in Chinese folk religion. In Japan he is venerated as a protector against smallpox and epidemics, and as a patron of academic success. He is portrayed with a long beard, dressed in official court robes, wearing a sword, and glaring demons into flight. He appears as early as late Heian-period apotropaic paintings, and later became a common motif for Boys’ Day and year-end or New Year talismans in hanging scrolls, dolls, and roof ornaments.