Chokai-san Omonoimi Legend

The Chokai-san Omonoimi legend records a mountain-cult and volcano-rite tradition for Mount Chokai (2,236 m) on the border of Yamagata and Akita. Omonoimi-no-Kami is an old volcanic deity tied to the activity of Chokai. Repeated eruptions from the ninth century onwards were reported to the court, and the deity's rank was raised in steps; the great eruption of 871 marked a particularly sharp ascent. The cult is structured in two tiers, with the mountaintop main shrine and the foothill shrines at Warabioka and Fukura, forming the Chokai-san Omonoimi Jinja. The tradition has three layers: volcanic activity and the manifestation of the deity; reports to the court and progressive elevation of rank; and the establishment of a summit-and-foothill rite system. Documentary sources are the Nihon Sandai Jitsuroku, Nihon Montoku Tenno Jitsuroku and the Engishiki Jinmyocho (927 CE), where the deity is listed as Akumi-gun Omonoimi Jinja Myojin-Tai. The shrine is the ichinomiya of Dewa Province; later transmissions include the medieval Omonoimi Jinja Engi and the Edo Dewa-no-Kuni Fudo-ryakki (1767), with further documentation in Yamagata prefectural and Yuza township resources.