Mizuchi, Midzuchi (蛟?) is a type of Japanese dragon or legendary serpent-like creature, either found in aquatic habitat or otherwise connected to water. Some commentators perceived it to have been a water deity. It is described in the ancient chronicle Nihon Shoki, and one Manyoshu poem.
Mizuchi is also the Japanese transliteration for several types of Chinese dragons (Shinmura 1976, Kojien dictionary, 2nd. ed.), and may refer to the jiaolong (; Japanese: kōryū) or "4-legged dragon", the qiulong ( or; Japanese: kyūryū) or "hornless dragon", and the chilong (; Japanese: chiryū) or "yellow dragon".
Daniels (1960:157) notes that rain-controlling Japanese snake deities are sometimes called dragons, but cautions that for okami and mizuchi, "it is unsafe to deduce their forms from the Chinese characters allotted to them".
The ancient chronicle Nihongi contains references to mizuchi. Under the 67th year of the reign of Emperor Nintoku (conventionally dated 379 AD), it is mentioned that in central Kibi Province, at a fork on Kawashima River (川嶋河, old name of Takahashi River in Okayama Prefecture), a great water serpent or dragon (大虬) dwelled and would breathe or spew out its venom, poisoning and killing many passersby.