Unagi (うなぎ) is the Japanese word for freshwater eels, especially the Japanese eel, Anguilla japonica. Saltwater eels are known as anago in Japanese. Unagi are a common ingredient in Japanese cooking. Unagi is served as part of unadon (sometimes spelled unagidon, especially in menus in Japanese restaurants in Western countries), a donburi dish with sliced eel served on a bed of rice. A kind of sweet biscuit called unagi pie made with powdered unagi also exists. Unagi is high in protein, vitamin A, calcium, cholesterol and saturated fat.
Specialist unagi restaurants are common in Japan, and commonly have signs showing the word unagi with hiragana う (transliterated u), which is the first letter of the word unagi. Lake Hamana in Hamamatsu city, Shizuoka prefecture is famous throughout Japan as the home of the highest quality unagi; as a result, the lake is surrounded by many small restaurants specializing in various unagi dishes. Unagi is often eaten during the hot summers in Japan. There is even a special day for eating unagi, the midsummer day of the Ox (doyo no ushi no hi).