Note that the -hime (媛) on the end is the word for "princess", and that tsu (津) appears in Old Japanese as the genitive particle, which was sometimes omitted from names.
Genealogy
There is no mention of her parents in either the Nihon Shoki or the Kojiki.
According to the Kojiki, she is the sister of Ata no Wobashi no kimi (阿多之小椅君,"Lord Wobashi of Ata"). The Kojiki also lists one Hayato no Ata no kimi (隼人阿多君, "Lord Ata of the Hayato") as a descendant of Hoderi. Meanwhile, according to the Genealogical Catalogue of the Ancient powerful families(古代豪族系図集覧) by Tositaka Kondo(近藤敏喬), her older brother is Amasori(天曽利), ancestor of Ata no Wobashi no kimi.
This Ata no Wobashi no kimi seems to be the same person as Ata no kimi Wobashi who appears in the Nihon Shoki as a descendant of Hosuseri.[1] As such, some have pointed to a connection between this person and the Hayato people that also appear in the Nihon Shoki as descendants of Hosuseri.[2]
According to Nihon Shoki, Emperor Jimmu (then a prince) took Princess Ohiraizu as his consort while he was in Hyūga before he made the Eastern Expedition.
^ abcdeNihongi: Chronicles of Japan from the Earliest Times to A.D. 697, translated from the original Chinese and Japanese by William George Aston. Book II, page 73. Tuttle Publishing. Tra edition (July 2005). First edition published 1972. ISBN978-0-8048-3674-6
^ abcde"According to the 'Kojiki', the great 8th century A.D. compilation of Japanese mythology, Konohana Sakuya-hime married a god who grew suspicious of her when she became pregnant shortly after their wedding. To prove her fidelity to her husband, she entered a benign bower and miraculously gave birth to a son, unscathed by the surrounding flames. The fire ceremony at Fuji-Yyoshida recalls this story as a means of protecting the town from fire and promoting easy childbirth among women."
^ abcAkima, Toshio (1993). "The Origins of the Grand Shrine of Ise and the Cult of the Sun Goddess Amaterasu Ōmikami". Japan Review. 4 (4): 143. ISSN0915-0986. JSTOR25790929.