Sukuyodo (a type of astrology) (宿曜道)

The term "Sukuyodo" refers to a kind of astrology which was brought to Japan as a part of the Esoteric Buddhism by priests who studied abroad such as Kukai in the Heian period. It is also called the Esoteric Buddhism astrology or Sukuyo astrology.

Summary
It is a synchronization of the Indian astrology (syncretization of Western astrology originated from Greece and moon astrology originated from India), the faith of heavenly body's god originated from Taoism, The Theory of Five Elements in Yin-Yang and so on.

Basically, a chinichi (a specific day on which a heavenly body exerts an influence on the Earth) is determined based on the movements of the celestial bodies—such as the Big Dipper, Kuyo (the nine primary celestial beings), the twelve signs of the zodiac, nijunanashuku (twenty-seven mansions of the Chinese constellation) or nijuhachishuku (twenty-eight mansions of the Chinese constellation)—and the rotation of what were known as the "seven luminaries", and if Kyo (bad fortune) was predicted, the gods of the star in question were enshrined to bring good fortune.

It is based on the scriptures of "Sukuyokyo sutra" (宿曜経), "Bontenkarakuyo" (梵天火羅九曜), "Shichiyoshoshinbetsugyoho" (七曜星辰別行法) and so on. It has a unique technique named Sankunohishuku.
A simplified version of this technique is generally used as 'Sukuyo astrology.'

In the Esoteric Buddhism, it was determined that a lucky day should be chosen for the events such as making a statue, Shuho (an esoteric ritual) and kanjo (a ceremony to be the successor). In "Dainichikyo-sho" written by Ichigyo, choosing a lucky day was regarded as an important task which showed the ability of Ajari (a master in esoteric Buddhism; a high priest).

For this reason, Kukai, Ennin, Enchin and others asked to bring "Sukuyokyo sutra" to Japan, and Ninkan studied it deeply. Nichien brought Futenreki (the Futian calendar table) from Wu-yueh in 957, which made its study active. In 963 Hozo (Japan) made a dispute with KAMO no Yasunori of Onmyodo (way of Yin and Yang; occult divination system based on the Taoist theory of the five elements) over the date of 御本命供 of the Emperor Murakami in those days. Therefore, it seems that Sukuyodo in Japan was established around this time. In addition, "Nichureki" (Dual History) regards Hozo as a founder of Sukuyodo in Japan. By such a development, most of the sukuyoshi (master of astrology based on the Sutra of constellations and planets) were priests of the Esoteric Buddhism. They cast a horoscope based on a birthday and made 'Sukuyo kanmon' (a report of Sukuyo) in which the result was written. In 995, 'an imperial decree to make a calendar' with Rekido (scholars of calendar) was given to Ninso (a priest) of the Kofuku-ji Temple (although the Kofuku-ji Temple was a temple of the Hosso sect, it was regarded to have a strong relationship with the Shingon sect). However, Rekido and Sukuyodo made a conflict in 1038 and Sukuyodo gave up making a calendar. It continued to fight with Rekido over the date and time of solar and lunar eclipses, daisho tsuki (months which had 31 days or 30 days), or leap months. In addition, tied with an influential person through the works of Sukuyo kanmon or prayers such as Hoshiku (Buddhist service for celebrating the star of a person's born year) and Saigu (festivals with altarage), some Sukuyoshi were assigned to betto (the superior of a temple) of the Horyu-ji Temple, the Saidai-ji Temple (Nara City) and so on. In the latter part of the Heian period, Nosan and his son Myosan (明算) flourished and served the Emperor Shirakawa and Sekkan-ke (the families which produced regents). In the end of the Heian period, there appeared two excellent Sukuyoshi named Chinga (珍賀) who belonged to the Tendai sect and Keisan (慶算) who belonged to the Kofuku-ji Temple and the Shingon sect. In collaboration with a person in authority, they fought each other to gain influence, and in doing so they improved their skills in so many ways that their family members and/or disciples formed new schools. However, Sukuyodo went to ruin in accordance with a decline of the noble society after the period of the Northern and Southern Courts (Japan). After Hokutorinkoin (北斗降臨院), which was established as a base of Sukuyodo by Chinga in 1165 and burnt down in 1417, it disappeared from the history.

In the volume of Kiritsubo in "The Tale of Genji" there is a scene that when the main character Hikaru Genji was born, Sukuyoshi told his fortune.