“Tamayorihime’s themes are cleansing, health, children and water. Her symbol is water (especially moving water or saltwater). An ancient Japanese sea Goddess, Tamayorihime rules not only moving water sources but also all matters of health. She also watches over birth waters to ensure a speedy, safe delivery for pregnant women.
The Tenjin festival began in 949 C.E. as a way to get rid of summer maladies. If you’ve had a cold, the flu or some other ailment, try an adaption of Japanese custom. Take a piece of paper that you’ve left on your altar for a while and rub it on the area of your body that’s afflicted. Drop the paper into moving water (like the toilet) to carry away sickness in Tamayorihime’s power. Alternatively, burn the paper to purge the problem. Mingle the ashes with a few drops of saltwater and carry them in a sealed container as a Tamayorihime amulet for health.
For personal cleansing and healing, soak in an Epsom-salt bath today. As you lie in the tub, stir the water clockwise with your hand to draw Tamayorihime’s health to you, or counterclockwise so She can banish a malady. If time doesn’t allow for this, add a very small pinch of salt to your beverages and stir them similarly throughout the day, while mentally or verbally reciting this invocation:
‘Health be quick, health be kind, within this cup the magic bind!’
Drink the beverage to internalize Tamayorihime’s energy.”
(Patricia Telesco, “365 Goddess: a daily guide to the magic and inspiration of the goddess”.)
Patricia Monaghan says that “like her sister Japanese heroines Ikutamayorihime and Seyadatarahime, she was a young woman who became a mother ancestor to an important family after mating with an otherworldly creature. This being used to come under cover of darkness, which apparently did not disturb the girl until she became pregnant. Then, to discover his identity, she sewed a long hemp thread to his hem, and, next morning, followed it to a dark cave. At its mouth she called out for her lover to show his face. ‘You would burst with fright,’ a deep voice answered from the earth’s center. Unafraid, she continued to make her demand until he appeared, a scaly monster with a needle stuck in its throat. Tamayorihime fainted, but lived to bear the hero Daida, greatest warrior of Kyushu. The heroine’s name, meaning a woman (hime) possessed (yor) by a god (tama), may have been a title borne by the Japanese shamans called miko. Similar stories are told of Psyche and Semele” (p. 291).
In the book Spirit Tree: Origins of Cosmology in Shintô Ritual at Hakozaki by E. Leslie Williams, I was able to find reference to Tamayorihime as an “earth-bound Female spirit cognitively linked with the ocean depths…a daughter of the sea deity, Watatsumi, in the Kojiki and Nihon Shoki myth cycles.”  “She appears in the KOJIKI as the mother of Emperor Jinmu (Jimmu). In this case She appears accompanied by two other deities and the three together are known as the Mikomori Sannyoshin. ” 
Mizue, Mori. Encyclopedia of Shinto, “Tamayorihime“.
Monaghan, Patricia. The New Book of Heroines and Goddesses, “Tamayorihime”.
Onmarkproductions.com, “Mikumari Myōjin Shrines“.
Williams, E. Leslie. Spirit Tree: Origins of Cosmology in Shintô Ritual at Hakozaki.
Faure, Bernard. The Power of Denial: Buddhism, Purity, and Gender.
Greve, Gabi. Wkdfestivalsaijiki.blogspot.com, “Samekawa Ablutions“.
Mizue, Mori. Encyclopedia of Shinto, “Tamayoribime“.
Wikipedia, “Shinto shrine“.