History

The Engi Shiki has a listing for an Arei Jinja (阿礼神社) in Shinano Province, Chikuma-gun and it is thought that this may be the current Arei Jinja. When it was founded is unclear but the shrine legend links it to Susano-o, saying that after slaying the Yamata Orochi in the upper reaches of the Hikawa river in Izumo he materialized at Arahikoyama (荒彦山) in the upper reaches of the Shiokawa river in Shinano Province and destroyed another demon. It is probable that Arahikoyama is the mountain now called Iodo-san（五百渡山). This meritorious feat is said to be the origins of the shrine. In 807, during the Daidō Period, Sakanoue Tamuramaro is said to have relocated the shrine to where the rear shrine is now located, a place then known as Myōjintaira (明神平). In September 851, Year 1 of the Ninju Period, the shrine's credibility was greatly enhanced when the then gūji was able to enlist divine help in stopping an epidemic which had broken out. The following year  another shrine was built in front of the