Omononushi is a deity in Japanese mythology. The deity Omononushi is enshrined in Omiwa-jinja Shrine. In "Izumo kokuso kamuyogoto" (ritual greetings by the highest priest of Izumo Taisha Shrine to the Emperor), he is mentioned as Omononushi kushimikatama. The deity enshrined in Omiwa-jinja Shrine is considered to be the peaceful spirit of Onamochi (Okuninushi). He is also called "Miwa-myojin."
According to Kojiki (The Records of Ancient Matters), the deity Sukunabikona no kami, who had been working with the deity Okuninushi to build this country, left for Tokoyo (lit. "the normal world," though some texts hint that it is the afterworld) leaving Okuninushi alone. Okuninushi was at loss about what to do next to build the country. Then, he saw a shining deity coming from beyond the sea and the deity wanted Okuninushi to enshrine him in Mt. Miwa in Yamato Province. Who are you,' asked Okuninushi. I am your Saki mitama (soul that makes people happy by luck) and your Kushi mitama (a soul that makes people happy with miracles),' he answered. According to an opinion cited in Nihonshoki, Okuninushi no kami is also referred to as Saki mitama or Kushi mitama. The history of Omiwa-jinja Shrine says that Okuninushi no kami enshrined his own Nikimitama as Omononushi-no-mikoto.
Having heard people say that Seyadatarahime, the daughter of Mishima no mizokui, was a beauty, Omononushi who fell in love with her at first sight. Wanting to talk to her somehow, he turned himself into a red arrow and waited. When he saw her coming to a river to relieve herself the arrow started to flow down the stream. When it came beneath her, it stuck into her nether regions. When she brought the arrow back to her room, it changed back into Omononushi, and then they made love. This was how Himetataraisuzu hime (Isukeyori hime), the future empress of Emperor Jinmu, came into being.
Suddenly, there appeared a handsome man in front of Ikutamayori bime, a daughter of Suetsumimi no mikoto, and they made love. To her dismay, she soon became pregnant. Worrying about her, her parents questioned her about what had happened. At last, she confessed that she had a handsome man coming to her every night although she did not know who he was. Anxious to know who he was, her parents told her to get a linen thread on a spool through a needle and to attach it to the hem of his garment. Next morning, peering through a keyhole, they saw the tread going out extending all the way to a shrine on Mt. Miwa as they tracked it.
As there were only three rolls ("miwa," literally "three rings") of thread left on the spool, the place where the other end of the thread was found got the name of 'Miwa.'
On the other hand, Omononushi told Emperor Sujin to have Ootataneko enshrine him. This is how today's Omiwa-jinja Shrine was built.
Omononushi has many characters; he is a Hebigami (god of snakes), Suijin (god of water), and Raijin (god of lightning). He has been worshipped by people who pray for good rice harvest, the warding off of evil, and the protection of the sake brewing business. He is believed to be a guardian of this country, but at the same time, to have the power to curse people.
In Haibutsukisyaku (the anti-Buddhism movement), that started in the first year of the Meiji period, many temples adopted Omononushi-no-mikoto as their enshrined deity, replacing their Honzon (the principle image of Buddha) that had been worshipped for a long time.
An example of this was Kotohira-gu Shrine in Kotohira-cho, Nakatado-gun, Kagawa Prefecture. Kotohira-gu, which had been a temple, became a Shinto shrine, replacing Kubira Taisho, one of Juni Shinsho (twelve heavenly generals of Yakushi Buddha), worshipped as the principle image, with Omononushi no mikoto. However, many reforms carried out by the Meiji government, whose policy revolved around the restoration of imperial rule, conformed to the ancient records of registered Shinto shrines. In general, a shift from Buddha to Shinto deities of Izumo (the heartland of Japanese mythology) took place in a systematic way.