J-pop and Kayōkyoku

J-pop, an abbreviation for Japanese pop, is a musical genre that entered the musical mainstream of Japan in the 1990s.
The origin of modern J-pop is said to be Japanese-language rock music inspired by The Beatles.[1]

Modern J-pop has its roots in 1960s pop and rock music, such as The Beatles, which led to Japanese rock bands such as Happy End fusing rock with Japanese music in the early 1970s.^[1]

Kayōkyoku (歌謡曲^?, literally "Lyric Singing Music", a term for Japanese pop music from the 1920s to the 1980s) is a Japanese pop music genre, which became a base of modern J-pop.  
Kayōkyoku is Western-style-inspired music of Japan. Music in this genre is extremely varied as a result.
The singers of the kayōkyoku genre, although there are some exceptions, do not use stylized pronunciations based on the English language, but prefer traditional Japanese.^[4]

J-pop was further defined by New Wave groups in the late 1970s, particularly electronic synthpop band Yellow Magic Orchestra and pop rock band Southern All Stars.^[2]

Eventually, J-pop replaced kayōkyoku in the Japanese music scene.^[3]