Prince Onamuji, the Ōnamuchi-no-mikoto, later called Ōkuninushi, was the last son of a minor god and one of his wives, Princess Kushinada. He had eighty older brothers, and as the youngest he was perceived as the weakest, and was constantly bullied. It was decided that their clan was to merge with the land of Inaba, and so all eighty-one princes were sent to seek the hand of Inaba's Princess Yakami. As the brothers traveled, they passed a flayed hare who was suffering greatly. The older brothers advised the hare to bathe in the sea, and they all laughed and proceeded on with their journey as the hare was tortured further. Onamuji, who was traveling behind them, saw what his brothers had done and helped the hare bathe in fresh water and roll in the down of cattail plants. Soothed, the hare immediately transformed into a god, and foretold that Prince Onamuji would be the one to win Princess Yakami's favor.
Charmed by his kindness, Princess Yakami did indeed choose Prince Onamuji to marry. Unfortunately for Onamuji, his eighty brothers were furious, and they conspired to each kill him twice over. His mother petitioned the creator goddess Musubi for help, and Musubi dispatched two of her daughters, Princesses Kisagai and Umugi, to resurrect him after each death. After one hundred and sixty deaths, his mother pleaded with him to flee to the underworld and ask their great ancestor Susa-no-O for advice. Onamuji reached the underworld, and was received by Susa-no-O's daughter, Princess Suseri. Onamuji and Suseri immediately fell in love, but Susa-no-O was skeptical of what was essentially the runt of the litter and his baby girl, thus tasked him with a plague of horrific missions to complete in hell to prove himself. Onamuji (occasionally with Suseri's help) completely the tasks, and ultimately impressed Susa-no-O enough to not only let him marry his daughter, but give him the advice he came for. He gave Onamuji his weapons and koto, and told him to fight his brothers in battle.
Onamuji and Suseri returned to the living world, collected Yakami, and went to war with the other eighty princes. Onamuji was the victor, and thus became the ruler of Izumo (modern day Chūgoku region). Together with the god Sukunabiko, Onamuji completed the creation of the Japanese islands begun by the high creation deities Izanagi and Izanami. His long reign ended when the goddess of the universe, Amaterasu (who is the sun), sent her grandson Ninigi to oversee the region. As compensation and, you know, a kind of apology for his horrific suffering, Izanagi made Onamuji a god, the ruler of the unseen world of spirits and magic.
As a god, Onamuji is called Ōkuninushi, and is the Shinto patron of nation-building, farming, business, and medicine, called a god of marriage in some Shinto sects.
Identity: Ōkuninushi, Shinto god, ruler of the spirit world and magic.
Real Name: Onamuji, Ōnamuchi-no-mikoto. "Mikoto" essentially means "spirit important to Shinto", but it's also (helpfully) a unisex given name.
Powers: Is a god! Essentially omnipotent in all realms, though specifically he has dominion over magic and the spirit world (the "spirit world" in Shinto is not the dead, it's the living spirit inside all things). He also has an affinity for the underworld, having such strong connections with it; the weapons he possesses are from hell, his queen is a native, and he spent quite a lot of time there uh, being tormented. But now he gets on well with the rulers and the condemned.
Associations: Mikoto is a brilliant strategist and general but not much of a warrior. If he has to be an active combatant, he'll use a bow. He is musically inclined, and favors the koto and piano. Rabbits tend to like him. He favors hard workers and entrepreneurs.
Personality: Mikoto is easy-going and pleasant, preferring peaceful living, especially now that he's 'retired'. He likes hanging out and playing music, and is, as a mortal, a music teacher. He holds court (or will) in the spirit world when necessary, and is a kind and pragmatic ruler who is overall really well-loved; he's never been unseated or had his position contested, and is one of the few demigods to be promoted so highly. He's very caring and a bit of a fixer, though in his old age he prefers to try and motivate people versus offer them presents. He has a good relationship with both of his wives (Suseri is his first wife and thus his queen, Yakami is his second wife and consort) and they've lived happily and harmoniously for a very long time now. He's not a pushover or a pacifist, however, and if he's tested enough he'll come back at you - neatly, though, he's not about to get into any bar fights.