It is an imperial grand festival, and a rite to present new grains to Amaterasu Omikami (the Sun Goddess). In the past, sacred sake and food offered to the god was given to an imperial envoy on September 11 (old calendar), and it was presented to the god on September 17 (old calendar). After the change to the solar calendar in 1872, the Kannamesai was also changed to be performed on September 17 on the new calendar, which was too early for the new grain, and therefore it was postponed by one month to be performed on October 17 on the new calendar since 1879.
Since the ancient times, the Imperial Family used to dispatch Heihakushi (a messenger who brings a sacramental strip of paper (silk)) to Ise-jingu Shrine on the Kannamesai, but the dispatch was often stopped after the Onin War. Since the dispatch of the Heihakushi started again in 1647 in Edo period, the dispatch has continued until now.
Since 1871, the rite of the Kannamesai has been also performed in Kashikodokoro (Palace Sanctuary) of the imperial court. Prior to the rite of the Kannamesai, the emperor bows the knee to Ise-jingu Shrine from away in the southern peripheral space of Shinka-den, one of the Three Shrines in the Imperial Court. In 1873, the day the Kannamesai was made a public holiday as a festival day.
After the war, due to the enforcement of Act on National Holidays, it is not a national holiday anymore, and the rite is performed only in the Three Shrines in the Imperial Court and Ise-jingu Shrine. The Heihaku and an imperial envoy (ceremonial staff) are dispatched from the Imperial Family to the Ise-jingu Shrine to service hohei no gi (ceremony for offering a wand with hemp and paper streamers to a Shinto god).
Kanname' is said to have been changed from 'Kami no ae.'
Ae' is an ancient word that means to offer hospitality with food. There is another opinion that ae was turned from nie that means new grains.
In Ise-jingu Shrine, all of the costumes and ceremonial implements are changed to new ones at the time of the Kannamesai. It is also called New Year of Ise-jingu Shrine. The transfer of a deity to a new shrine building once in twenty years is said to be in fact large scale Kannamesai. In Ise-jingu Shrine, the first Kannamesai after the transfer of the deity is also called 'Okannamesai' meaning great Kannamesai. People in Ise City call the festival 'Omatsuri,' in which various celebration events are performed. It is said that Shinto priests in Ise-jingu Shrine and Shinryomin of Ise do not eat new grain until the festival ends, but it is not known whether the rule is actually kept.
Kannamesai is an autumnal season word.
Both Shogu and major shrines hold events according to the schedule in the chart below.
Other shrines hold events according to the following schedule.
Sonai Junkai: Kawara, Sonai, Kugutsuhime, Ogoso, and Narahara Jinja Shrines
Oma Junkai: Takagawara, Kiyonoiba, Omakunari, Obata, Shitomi, Okochi, Uchikake, Wataraikunimi, Otsu, Kaminomiino, and Shimonomiino jinja Shrines
Kano Junkai: Kamoshimo, Tanoe, Tanoemimae, Kamo, Tsubura, Kano, Kanomimae, and Kuchira jinja Shrines
Okunitama Junkai: Wataraiokunitamahime, Igari, Inaka, Yamazue, Tanoeomizu, Tanoeomizumimae, Kawarabuchi, Mike, Shioya, Kawara, Mori, Usunono, and Agata jinja Shrines
Yuta Junkai: Yuta, Satakunari, Sakatekunari, Sugihara, Mifune, and Mumino jinja Shrines
Otsuchi Junkai: Tsunaga, Niikawa, Iwai, Omizu, Kawaai, Kumabuchi, Aedohashihime, Oyamatsumi, Koyasu, Ujiyoda, Najime, Ashihara, Otsuchimioya, Ujinonuki, Kunitsumioya, and Ashidate jinja Shrines
Hatadono Junkai: Hatadono-jinja Shrine
Akasaki Junkai: Akasaki-jinja Shrine
Katada Junkai: Kanumi, Mishiodono, Katada, E, Kozaki, Komori, Arasaki, and Awamiko jinja Shrine