Nitsume

Kabayaki is a preparation of fish, especially unagi eel, where the fish is split down the back (or belly), gutted and boned, butterflied, cut into square fillets, skewered, and dipped in a sweet soy sauce-based marinade before being cooked on a grill or griddle. Besides unagi, the same preparation is made of other long scaleless fish such as hamo (pike conger), dojō (loach), catfish, anago (conger eel), and gimpo (ギンポ) (gunnels). One can also find canned products labeled as kabayaki-style sanma (Pacific saury). Kabayaki eel is very popular and a rich source of vitamins A and E, and omega-3 fatty acids. A popular custom from the Edo period calls for eating kabayaki during the summer to gain stamina, especially on a mid-summer day called doyō-no ushi-no-hi [ja] (土用の丑の日), which falls between July 18 and August 8 each year.

Source: Wikipedia