Saiō (斎王) or itsuki no miko^[1] was the title of the unmarried female members of the Japanese Imperial Family, sent to serve at Ise Grand Shrine from the late 7th century to the 14th century. The saiō's residence, Saikū (斎宮), was about 10 km (6.2 mi) north-west of the shrine. The remains of Saikū are situated in the town of Meiwa, Mie Prefecture, Japan.^[2]

According to Japanese legend, around 2,000 years ago the divine Yamatohime-no-mikoto, daughter of the Emperor Suinin, set out from Mount Miwa in Nara Prefecture in search of a permanent location to worship the goddess Amaterasu-ōmikami.^[3] Her search lasted for 20 years and eventually brought her to Ise, Mie Prefecture, where the Ise Shrine now stands.^[4] Prior to Yamatohime-no-mikoto's journey, Amaterasu-ōmikami had been worshiped at the Imperial Palaces in Yamato.

According to the Man'yōshū (The Anthology of Ten Thousand Leaves), the first saiō to serve at Ise was Princess Ōku, daughter of Emperor Tenmu, during the Asuka period of Japanese history. Mention of the saiō is also made in the Aoi, Sakaki and Yugao chapters of The Tale of Genji, as well as in the 69th chapter of The Tales of Ise (Ise Monogatari).

In the 13th century, Jien recorded in the Gukanshō that during the reign of Emperor Suinin, the first High Priestess (saiō) was appointed for Ise Shrine.^[5] Hayashi Gahō's 17th-century Nihon Ōdai Ichiran is somewhat more expansive, explaining that since Suinin's time, a daughter of the emperor was almost always appointed as high priestess, but across the centuries, there had been times when the emperor himself had no daughter; and in such circumstances, the daughter of a close relative of the emperor would have been appointed to fill the untimely vacancy.^[6]

The role of the saiō was to serve as High Priestess at Ise Shrine on behalf of the Emperor, to represent the role first set out by Yamatohime-no-mikoto. Three rituals a year were conducted at the Shrine in which the saiō prayed for peace and protection. In June and November each year, she journeyed to the Shrine to perform the Tsukinamisai Festival. In September in the lunisolar calendar, she performed the Kannamesai Festival to make offerings to the kami of the year's new grain harvest.^[7]

For the rest of the year, the saiō lived in Saikū, a small town of up to 500 people approximately 10 km (6.2 mi) north-west of Ise, in modern Meiwa, Mie Prefecture. Life at Saikū was, for the most part, peaceful. The saiō would spend her time composing waka verses, collect shells on the shore of Ōyodo beach, or set out in boats and recite poetry upon the water and wait to be recalled to Kyoto.^[7]

When an Emperor died or abdicated the throne, when the saiō's relative died, or when certain political power required, she would be recalled to the capital and a new saiō selected from one of the new Emperor's unmarried female relatives using divination by either burnt tortoise shell or deer bones. The new saiō would then undergo a period of purification before setting out with her retinue of up to 500 people for Saikū, never to return to the capital until recalled by the next Emperor.

Upon the selection of the new saiō, the current saiō and her retinue would return to the capital to resume their lives as part of the Imperial Court. Often a saiō was quite young when she left the capital for Saikū, and would only be in her mid-teens or early twenties when she returned to the capital. It was considered a great honor to marry a former saiō and her time at Saikū improved her own position at court and those of the people who served with her.

The procession routes of the saiō changed after the capital was moved to Heian-kyō in 794.

The procession began in what is today the Arashiyama district on the west side of Kyoto. In the Heian period, successive imperial princesses stayed in the Nonomiya Shrine for a year or more to purify themselves before becoming representatives of the imperial family at the Ise Shrine.^[8] Contemporary annual processions recreate a scene from a picture scroll of the imperial court during the Heian period, starting from the shrine and continuing as far as the Togetsu-kyo Bridge, Arashiyama.^[9]

The procession of the saiō from Kyoto to Saikū, the saiō's official residence in Ise, was the largest procession of its kind in Japan for its time. Up to 500 people would set out from Kyoto as a part of the saiō's retinue for the journey, which lasted six days and five nights. From Kyoto, they travelled in an eastward direction, passing through the Suzuka Pass, which was without doubt the most difficult part of the journey. Once clearing the pass, the retinue would descend into the Ise region and turn south, eventually reaching the Kushida River (櫛田川). Here, the saiō would stop to perform a final cleansing ritual before crossing the river and travelling the short distance to Saikū.^[10]

The saiō was expected to remain at Saikū until the emperor whom she represented either died or abdicated the throne. The saiō was permitted to return to Kyoto only on the provision of a close relative's death. When returning to Kyoto, a different route was taken through the mountains to Nara, then to Osaka Bay where a ceremony was to be performed before she could finally return to the capital.

It is not precisely clear when the saiō system ended, but what is known is that it occurred during the turmoil of the Nanboku-chō period when two rival Imperial courts were in existence, in Kyoto and Yoshino. The saiō system had been in steady decline up to this period, with Saikū reverting to just another rural rice farming village after the system's collapse.

Though the area of Saikū remained, it was unclear exactly where the old Imperial town stood until pottery remains were unearthed in 1970 during the construction of housing in the Saikū area, Meiwa Town. A modern museum was built on the site of the first finds and archaeological excavations are continuing, held each summer with the aid of volunteer school children from all over Japan. Though a site for the main saiō residence has been discovered, a large percentage of it lies beneath the main Kintetsu Ise railway line and is inaccessible. Itsukinomiya Historical Experience Hall, a reconstruction of the building using traditional techniques, was built in the 1990s and stands beside Saikū station on the local Kintetsu rail line, no more than 200 metres (660 ft) from the original site.

The Aoi Matsuri, the first of the three main festivals held in Kyoto each year, re-enacts the Heian period march of the saiō to the Shimigamo Shrine (lower Kamo Shrine) in Sakyo Ward. This festival is held every year on May 15 and in 2006 consisted of 511 people dressed in traditional Heian court clothing and 40 cows and horses, stretching around 800 m (2,600 ft) from start to finish. This festival is said to have started in the 6th century when the Emperor sent his representatives to Shimogamo and Kamigamo Shines to pray from good harvests.

The Saiō Matsuri is held in the town of Meiwa, Mie Prefecture, on the first weekend of June each year. First held in 1983, it re-enacts the march of the saiō from her residence at Saikū, to the nearby Ise Shrine. More than 100 people dressed in traditional Heian-period dress along a section of the old Ise kaido (pilgrimage road), before ending in the grounds of the Saikū Museum.

After the establishment of the saiō system by Emperor Tenmu, these were priestesses of Ise Shrine.