Umashiashikabihikoji is a god appearing in Japanese mythology. It was one of the Kotoamatsu Kami (literally, separate heavenly kami) (Japanese mythology) appearing during the creation of heaven and earth. It is written Umashiashikabihikoji no Kami (宇摩志阿斯訶備比古遅神) in Kojiki (The Records of Ancient Matters), and Umashiashikabihikoji no Mikoto (可美葦牙彦舅尊) in Nihonshoki (Chronicles of Japan).
In Kojiki, it is described as the god created by matter growing like budding reed, after the appearance of Zoka-sanshin (three gods of creation), when the world on earth was like oil floating on water, drifting around in chaos like jellyfish. In other words, it is the fourth god. It is not described in the main body of the Nihonshoki. It is described as the first god to appear in the Arufumi (supplement volumes of explanatory notes in Nihonshoki) Vol. 2 and 3, and the second god to appear in the Arufumi Vol. 6. It is a hitorigami (god without gender) who is described as having gone into hiding immediately, with no comment on the circumstances, and does not appear in Japanese mythology thereafter.
The word 'Umashi' in the shinmei (name of god) is a eulogistic name for something good, as in 'umashi-kuni.'
The word 'Ashi' is reed, 'kabi' is cognate with mold, meaning something that ferments and buds.
Here, 'ashikabi' means the 'reed buds.'
Thus, it is a god deifying the vitality of all things symbolized by reed buds. In general, it is considered a god of vitality.
The word 'Hikoji' means a male, but this god is a hitorigami and has no gender. It is believed that due to the vigor of reeds budding, it was considered the 'god of yang,' influenced by the cosmic dual forces ideology introduced from China, and the word 'hiko' which is indicative of male was included in the shinmei.
It is enshrined in the Honden (main shrine) Okyaku-za of Izumo-taisha Shrine (Izumo City, Shimane Prefecture), Ukishima-jinja Shrine (Toon City, Ehime Prefecture), etc.