The Yato-no-kami (夜刀の神, "gods of the night-sword") are snake deities in Japanese folklore appearing in the Hitachi no Kuni Fudoki.
They lived in Namegata county, in fields near the government office.
As a snake, it was an araburu-kami (荒ぶる神, "rough, aggressive kami") which are fierce kami who represent the ferocious side of nature, such as raging rivers and fierce storms - as well as natural disasters.
It's told that Yato no Kami were killed and enshrined by a man named Yahazu no uji no Matachi during the time when Emperor Keitai was in reign.
The Yato no kami vanished later when a man named Mibunomuroji Maro drove them away from disturbing him and his workers who were building a moat there.