Japan occupied Korea as a colony from 1910 to 1945. South Korean musicians have been successful in Japan since the inception of Korean popular music. There have been a number of ethnically South Korean singers who have gained fame in Japan. Some of these singers, including Choi Gyuyeop/Hasegawa Ichiro and Yi Nan-yong/Oka Ranko were Zainichi, Koreans with Japanese residency.[1] Among these Zainichi artists, there were and still are some who have made public declarations of their Korean descent, and many more who were rumored to be Korean but have never made formal confirmations. Those who do divulge their heritage often do so after they have attained a relatively stable level of popularity. The act of revealing one's Korean ethnicity is called "coming out".[citation needed] Nevertheless, there were South Korean singers like Cho Yong-pil and Kye Un-seuk, in the 1970s and 1980s who were household names in Japan, despite not being Zainichi.[1] Today, there are also a number of non-Zainichi Korean artists such as BoA, Crystal Kay, TVXQ, BIGBANG, KARA, and BTS who have found chart and album success in Japan.
Many Korean singers who were famous in Japan sang trot music, an older genre of Korean pop music. This is partly because of trot's similarity to enka, a popular Japanese genre that resembles traditional Japanese music. The similarity between Japan's and South Korea's soundscape was due to stricter Japanese political control in the 1930s, when Japan taught Japanese shoka, Japanese-style Western music for children, in Korean elementary schools.[2]
In terms of popular music, or "yuhaengga" in Korean, many early hits were Japanese songs that had been translated into Korean. Nevertheless, many Koreans still contributed their own unique touch to the emerging field of pop music in Korea. For example, Japanese popular-music composer Koga Masao, who had grown up in colonial Korea, incorporated Korean elements like the use of three beats to create the Korean influenced "Koga melody."[1]