牛丼 (Gyudon) is a popular Japanese dish consisting of a bowl of rice topped with thinly sliced beef and onions simmered in a mildly sweet sauce made from soy sauce, mirin, and sake. It is often garnished with pickled ginger and sometimes a raw or soft-cooked egg. Gyudon is commonly served in restaurants and is a favorite for its comforting flavors and quick preparation. This dish is typically enjoyed as a fast meal and is widely available at fast food chains like Matsuya and Sukiya in Japan. Gyudon has become a staple in Japanese cuisine, appreciated for its simplicity and satisfying taste.