Kisagaihime and Umugihime (キサガイヒメ・ウムギヒメ)
Kisagaihime and Umugihime were gods (Shinto religion) that appear in Japanese Mythology. Each was described as '蚶貝比売' (Kisagahihime) and '蛤貝比売' (Umugihime or Umugahime) in "Kojiki" (The Records of Ancient Matters) and '支(枳)佐加比売命' (Kisakahime no mikoto) and '宇武賀比売命' (Umukahime no mikoto) in "Izumo no kuni fudoki" (the topography of Izumo Province).
It was considered that Kisagaihime was created by deifying an arch shell, and Umugihime was created by deifying a clam. They had a relationship with Kamimusubi in both 'Kojiki" and "Izumo no kuni fudoki," and it was written in the former that they were dispatched by Kamimusuhi no mikoto to engage in treating Okuninushi (chief god of Izumo in southern Honshu Island, Japan, and the central character in the important cycle of myths set in that region), and it was written in the latter that they were mikogami (the child god in a shrine where parent-child gods are enshrined) of Kamumusubi no mikoto.
Descriptions in the mythology
In the mythology of Okuninushi, it described that Okuninushi no kami, who was regarded with jealousy by his brother Yasogami, was burned to death by catching the burning rock rolling down from the top of the mountain when Yasogami lied the rock was a wild boar, then both of them were dispatched there by the order of Kamimusuhi no mikoto. Kisagaihime collected scraped powder ('kisagi atsume') and Umugihime received it and applied mother's milk, then Okuninushi was resuscitated.
In the description, there was a theory that it described a folk remedy to be used for burn injuries by powderizing the husk of an arch shell and mixing it with the white juice of a clam as milk. On the other hand, by focusing on the point that clam juice was used to resemble milk, there was a theory that it was used for resuscitation to expect acceleration of life force and efficacy of recovery that milk had, and one factor of mythology, 'resuscitation by milk' was created by arousing his Shinmyo 'Umu' by 'mother' (pronounce omo). In addition, a clam was described as 'Umuki no kahi' in "Wamyo-sho" (a dictionary compiled in the Heian period) and used as medication through the ages.
On the other hand, an arch shell was described as 'Kisa' in "Wamyo-sho" and it stated 'it was rounded and thick like clam and had crosswise lines,' so it could interpret that it was named after 'kiza' (growth rings) on the surface of the shell and 'kisage atsume' meant scraping husk of an arch shell to collect its powder ('kisagu' meant 'shave' and 'scrape'), but it was unknown what kinds of efficacy the arch shell had. It was certain that Kisagaihime was aroused by 'kisage atsume,' but it was not told how she was related to this narrative and Umugihime other than this point. Therefore, one theory said it sounded the tone of 'kaso' that was the ancient word of 'father' to 'kisa' of Kisagaihime and made her appear against 'Umu omo' (mother) of Umugihime.
"Izumo no kuni fudoki"
They appeared separately and the relationship other than they were mikogami of Kamumusubi no mikoto was not clearly stated. It was described that Kisakahime no mikoto gave birth to Sada no Okami (Great God of Sada) (an enshrined deity of Sada-jinja Shrine) in Kaka no kugedo (Shimane no kohori Kaka no sato and Kaka no kamuzaki) and Umukahime no mikoto became Hohokidori (bush warbler), flied to Hokki no sato (around present Hokki-cho, Matsue City, Shimane Prefecture), and was enshrined there (Shimane no kohori Hokki no sato).
In the narrative of Kisakahime no mikoto's childbirth in "Izumo no kuni fudoki," similarities with so-called Ninuri no ya (bright-red arrow) style mythology were evident, such as the narrative that Seyadatarahime gave birth to Himetataraisuzuhime in "kojiki" and the mythology that Tamayoribime gave birth to Kamowakeikazuchi no mikoto in "Yamashirono kunu Fudoki" Itsubun, (a lost writing of regional gazetteer for Yamashiro Province).
Both gods are enshrined in sessha Amasaki no yashiro (auxiliary shrine of Inochihime-jinja Shrine) of Izumo-taisha Shrine. Both gods are also enshrined in Kisa-jinja Shrine (Nishi Ward, Hamamatsu City, Shizuoka Prefecture). As for the shrines that enshrine each god, there is Kaka-jinja Shrine (Shimane-cho, Matsue City, Shimane Prefecture) for Kisagaihime no mikoto and Hokki-jinja Shrine (Hokki-cho Matsue City, Shimane Prefecture) for Umugihime no mikoto.