Onie no Matsuri Festival (大嘗祭)

The Onie no matsuri Festival is the first Niiname-sai Festival (ceremonial offering by a emperor of newly-harvested rice to the deities) solemnized by an emperor after his or her Sokui no rei (ceremony of enthronement). This is a grand festival that takes place only once in a generation, and is virtually the ritual of Senso (succession to the throne).
It is also called 'Senso Daijo-sai Festival,' 'Daijo-sai Festival' or 'Omube no matsuri Festival.'

Summary
The harvest festival solemnized by an emperor, every November is called the Niiname-sai Festival. The Niiname-sai Festival, in which an emperor devotes the Shinkoku (the first crop of the year) to the God and also eats it himself, was called 'Yearly daijo' in ancient times.
At the beginning, it wasn't separated from the regular Niiname-sai Festival, but later as a ritual, solemnized only once in an emperor's lifetime, it became important being called 'Daijo once in a lifetime' and 'Onie no matsuri Festival.'
It is said that the Onie no matsuri Festival and the Niiname-sai Festival have been separated ever since the Emperor Tenmu solemnized his Onie no matsuri Festival.

It is also said that the ritual outlines of Onie no matsuri Festival were established around the era of the Empress Kogyoku in the seventh century. As the Ritsuryo system (a system of centralized government based on the ritsuryo code) was established, the program of the festival was also decided in detail. The Onie no matsuri Festival was the only festival to be considered as a Taishi (the most important festival) amongst other festivals included in the Engishiki (an ancient book for codes and procedures on national rites and prayers).

The program was changed in a sort of way even after it was included in the Engishiki. Although it was often delayed or canceled due to the financial difficulties of the Imperial court or the maelstrom of war in the last stage of the Muromachi period, that is to say, the Sengoku period (Japan) (period of warring states), the Onie no matsuri Festival has been succeeded as an important ceremony related to enthronements of emperors since long ago.

The most recent Onie no matsuri Festival was solemnized in November 1990, accompanied by the enthronement of Emperor Akihito.

At that time, the rituals related to the Sokui no rei were considered a national event, and the rituals related to the Onie no matsuri Festival was treated as an event of the Imperial family.
It is sometimes misunderstood that 'an event of the Imperial family' means 'a private event of the Imperial family,' but it is actually 'a public event of the Imperial family.'
Obviously the extraordinary budget for the Onie no matsuri Festival is formulated separately to the emperor's family budget. According to the final announcement of the government at that time, the Onie no matsuri Festival was not considered as a state act, because unlike the emperor's state acts, which were not related to the state vaguely but needed advisement and authorization of the ministry, the Onie no matsuri Festival, a traditional noble ritual, was in a different category to the state acts belonging to the affairs of State, and thus was not considered as a state act.

Program
Please refer to the article of Sokui no rei about the specific dates of Sokui no rei and the Onie no matsuri Festivals in recent years.

Enthronement and the Onie no matsuri Festival
According to the Engishiki, the Onie no matsuri Festival was solemnized in same year as the emperors' enthronement if it took place before July, but was solemnized in the following year if the enthronement was held after August.

Yuki (the first province to offer the first rice crop of the year at the Onie no matsuri Festival) and Suki (place where the Onie no matsuri Festival takes place)
In the year, in which the Onie no matsuri Festival would be held, at first, Shoshi (Governor of the Board of Retainers) decided by fortunetelling a province and a county for the Yuki and the Suki in order to select the rice fields that would provide rice plants for the festival. The provinces of the Yuki and the Suki are called Itsuki no kuni. The Yuki was chosen from eastern Japan and the Suki was chosen from western Japan, but they never have been chosen from provinces in Kinai region. After the medieval period, Omi Province took the role of the Yuki, and Tanba Province and Bitchu Province swapped the role of the Suki; they decided by fortunetelling a county within the province.

The Yuki and the Suki after the Meiji period

The related rituals held before the month in which the Onie no matsuri Festival takes place
In early August, an Oharaeshi chosen by Bokujo (to decide by fortunetelling) was sent to Sakyo (east part of capital), Ukyo (west part of capital), Gokinai capital region, and each district of Shichido (the seven districts of ancient Japan) to perform exorcisms. Haraeshi were also sent to those regions and districts to perform exorcisms in late August. After performing the exorcisms, they presented heihaku (paper or silk cuttings or red and white cloth, presented to the gods) and notified Imperial instructions to every god of heaven and earth in Japan including Ise-jingu Shrine. Also, in late August, Nukihoshi (Imperial envoy sent to gather ears of rice) chosen by Bokujo were sent to Itsuki no kuni and they chose Saiden (rice fields to cultivate rice plants for deities), Saijo zoshikinin (lower-level functionaries in the provincial government) and Sakatsuko (girls brew sake presented to gods) by using Bokujo in those provinces. They gathered in ears of rice in September, making the first four sheaves they gathered into Mii (rice) and making the rest into Kuroki (black sake) and Shiroki (white sake) and presented them to the gods. The Mii, Kuroki and Shiroki were kept in a temporary building outside of the Saijoin building built in the Miyako (capital) from late September until the festival started. In late October, an emperor went to a river to perform Gyokei (purification ceremony). This Gyokei was performed inside of the Imperial Palace after the middle of the Edo period.

The rituals within the month in which the Onie no matsuri Festival takes place
The festival was held on U no hi (the day of rabbit) in November. If there were three U no hi in November, the second one used to be chosen, however, in after ages the last U no hi in November was chosen. Today, because the Niiname-sai Festival takes place on the Labor Thanksgiving Day, November 23, the Onie no matsuri Festival also takes place on the same day (the Onie no matsuri Festival of the present Emperor in 1990 was performed from the late-evening of November 22 to the early hours of 23).

In November, from the first day to the Misoka (last day of month) was Araimi (capsule Monoimi, 'avoiding something regarding as ominous'); the three days from Ushi no hi (the day of ox), right before the U no hi on which the festival was held, were Maimi (strict Monoimi) and associating with impurities was admonished during the period. They laid on the ceremony space for the Yuki and the Suki, building related facilities on the space for cooking and producing the Jinku (offering to gods), Miki (sacred wine or sake) and Chodo (furnishing). They started building the Daijo-gu (temporary shrine prepared at the palace for the Onie no matsuri Festival) seven days before the festival and completed within five days. The Daijo-gu consisted of the Yuki-den building and the Suki-den building.

The rituals of the Onie no matsuri Festival
The night of the day in which the festival is held, an emperor goes to the Kairyu-den building, taking Omi no oyu for purification, wearing Saifuku (priestly vestments), and after that, in the late-evening, goes into the Yuki-den building (the figure of Chigi [ornamental crossbeams on the gable of a Shinto shrine] is Sotosogi, or the ends of the former are terminated with a vertical cut, and is same as that of the Outer Shrine of Ise-jingu). In the Yuki-den building, there are Fusuma (bedding) put down in a southerly direction and a rack to place formal attire (court) and Kutsu (shoe, footwear) is put on the north side of the Fusuma. The pillow on the Fusuma is called Sakamakura. The bedclothes are Kamukura (the place of god) and emperors don't use them. In the Yuki-den building, emperors present Shinsen (food and alcohol offering to the gods) and notify Imperial instructions to the god; they Naorai (feast) the god, or they eat the Shinsen, presented to the god, themselves. Later emperors go back to the Kairyu-den building once again and then go into the Suki-den building (the figure of Chigi is Uchisogi, or the ends of the former are terminated with a horizontal cut, and is same as that of the Inner Shrine of Ise-jingu), to repeat what he did in the Yuki-den building.

Adjunct rituals
Other than this main ritual, there are more events such as Amatsukami no yogoto presented by the Nakatomi clan on Tatsu no hi (the day of dragon), Yamatomai Dance and Fuzokumai Dance on Mi no hi (the day of snake), and Gosechi no mai Dance (dance performance as part of a harvest festival).