(蒲焼), a grilled eel with a sweet sauce made of soy sauce and sugar after filleted and boned. An eel has been considered as nutritious and stamina-generating food in Japan. Many people eat Kabayaki in summer, especially on a particular day called "doyo-no ushi-no-hi (土用の丑の日). The custom is derived from that an owner of an eel restaurant consulted Hiraga Gennai, a famous herbalist and inventor about the decrease in sales in summer. He suggested him to put an advertisement at the door of the restaurant which catchphrase was "Today is the day of Doyo-ushi ", because people in those days believed in the tradition of eating dishes that began with the letter u on the day of "Ushi-no-hi" was good for the health. By the way, an eel is called Unagi (うなぎ) in Japanese.
Japanese sanshō (山椒) powder is indispensable for Kabayaki. Every elel restaurant has it on each table available and packed Kabayaki are always sold with it and a small bottle of sweet sauce.