Vodyanoi

Japanese: Vodyanoi

…The thunder god Perun occupied the highest position in the pantheon of Slavic gods. Lesser gods included the forest god Leshii, the water god Vodyanoi, and the water, forest, and air spirit Vila. The Slavs did not leave behind a clear mythology, and the functions of the gods are not always clear. …

From Slavic Mythology

Other examples of deification of historical figures include the Eastern Slavic Kii, Shchek, and Khoriv, and the Western Slavic Tsekh, Lyakh, and Krak, who are heroes of lineages that became the founders of communities and appear in mythological epics. Others include the Russian witch Granny Yaga, the immortal Koshchei, and Old Man Moroz the Cold, as well as many spirits associated with natural and cultural phenomena that appear in folk beliefs (such as the Russian water spirit Vodianoi, the forest spirit Leshii, the house spirit Domovoi, and the water and forest spirit Rusalka). It is thought that these figures and spirits of folk tales were once larger pagan deities.

From Russia

...The Leshi also act as the guardian deity of the forest. In rivers and lakes live the water spirits called vodyanoi, who rule over the world of fish. Their bodies are covered with scales and have membranes between their toes. ...

*Some of the terminology that mentions "Vodyanoi" is listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

Japanese:

…雷神ペルーンPerunはスラブの神々の神殿で最高位を占めていた。低位の神々には森神レーシーLeshii，水神ボジャノーイVodyanoi，水･森･空気の精ビーラVilaなどがあった。スラブ人は明確な神話を残さず，神々の機能は必ずしも明らかではない。…

【スラブ神話】より

…　以上あげたもの以外に，歴史上の人物が神格化した例として東スラブのキイKii，シチェークShchek，ホリフKhoriv，西スラブのツェフTsekh，リャフLyakh，クラクKrakなど共同体の始祖となった系譜上の英雄があり，神話的叙事詩に登場する。またロシアの魔女ヤガーばあさん，不死のコシチェーイ老人，寒さのモローズ爺といった昔話に登場する存在，民間信仰に現れる自然と文化の現象にちなんだ多くの精霊(ロシアの水の精ボジャノーイVodyanoi，森の精レーシーLeshii，家の精ドモボーイDomovoi，水と森の精ルサールカRusalkaなど)もスラブの神話世界を構成する。こうした昔話の形象や精霊はかつてはより大きな異教的神格であったと想像される。…