 Few rivers flow into the Sea of Japan from mainland Asia, the largest being Tumen, Rudnaya, Samarga, Partizanskaya and Tumnin; all of them have mountainous character.In contrast, numerous large rivers flow from Honshū and Hokkaidō into the sea, including Japan's four largest rivers in the Shinano, Ishikari, Agano and Mogami.The total annual river discharge into the sea is and is relatively constant through the year, except for a minor increase in July.