Mentaiko is the marinated roe of pollock, and is a common ingredient in Japanese cuisine. Mentaiko originated from myeongran jeot and was introduced to Japan after the Russo-Japanese War. Kawahara Toshio, a Busan-born Japanese, adapted Korean mentaiko to Japanese tastes in Fukuoka in the 1950s. The name is derived from the Korean word for Alaska pollock (mentai, myeongtae in Korean) and the Japanese word for "child" (ko). The typical seasoning and flavor is slightly different in Japan.
Mentaiko is made in a variety of flavors and colors and is available at airports and main train stations. It is usually eaten with onigiri, but is also enjoyed by itself with sake. A common variety is spicy mentaiko (karashi mentaiko). It is a product of the Hakata ward of Fukuoka City.