The River-Gods are prayed to for rain in time of drought. We hear oftener of their sinister aspect. The Perseus and Andromeda incident related above is probably a trace of former human sacrifices to rivers, of which further evidence is afforded by the following extracts from the Nihongi:
"A.D. 379. This year, at a fork of the River Kahashima, in the central division of the Province of Kibi, there was a great water-dragon which harassed the people. Now when travellers were passing that place on their journey, they were sure to be affected by its poison, so that many died. Hereupon Agatamori, the ancestor of the Omi of Kasa, a man of fierce temper and of great bodily strength, stood over the pool of the river-fork and flung into the water three whole calabashes, saying: 'Thou art continually belching up poison and therewithal plaguing travellers. I will kill thee, thou water-dragon. If thou canst sink these calabashes, then will I take myself away, but if thou canst not sink them, then will I cut thy body to pieces.' Now the water-dragon changed itself into a deer and tried to draw down the calabashes, but the calabashes would not sink. So with upraised sword he entered the water and slew the water-dragon. He further sought out the water-dragon's fellows. Now the tribe of all the water-dragons filled a cave in the bottom of the pool. He slew them every one, and the water of the river became changed to blood. Therefore that water was called the pool of Agatamori."
"A.D. 323. In order to prevent the overflowing of the Northern river the Mamuta embankment was constructed. At this time there were two parts of the construction which gave way and could not be stopped up. Then the Emperor had a dream, in which he was admonished by a God, saying: 'There are a man of Musashi named Koha-kubi and a man of Kahachi named Koromo no ko, the Muraji of Mamuta. Let these two men be sacrificed to the River-God, and thou wilt surely be enabled to close the gaps.' So he sought for
