Katsuo is in the family of migratory fish in the Pacific Ocean which go up north from Kyushu to southern Hokkaido in the spring and go down south in the autumn. ”Hatsugatsuo”, the first bonito in the year is caught in early summer and is cherished for its lower fat and light taste. “Modori gatsuo”, the bonito returning from the north and caught in the autumn contains more fat. Caught by big-scale offshore fishing vessels, bonitos are quick-frozen on board so that they can be eaten all year round. As well as being served raw as sashimi or tataki (where the outer portion of the fish only is heated), it is also used in simmered dishes and canned. It is used for Katsuo bushi and is abundant in inosinate.
Levels of naturally occurring glutamate（mg/100g）：1〜10
Levels of naturally occurring inosinate（mg/100g）：130〜270