stylistic:style_transfer, linguistic:voice_change, information:filtering
1920s–1960s: Ryūkōka

Japanese popular music, called ryūkōka before being split into enka and poppusu, has origins in the Meiji period, but most Japanese scholars consider the Taishō period to be the actual starting point of ryūkōka, as it is the era in which the genre first gained nationwide popularity. By the Taishō period, Western musical techniques and instruments, which had been introduced to Japan in the Meiji period, were widely used. Influenced by Western genres such as jazz and blues, ryūkōka incorporated Western instruments such as the violin, harmonica, and guitar. However, the melodies were often written according to the traditional Japanese pentatonic scale. In the 1930s, Ichiro Fujiyama released popular songs with his tenor voice. Fujiyama sang songs with a lower volume than opera through the microphone (the technique is sometimes called crooning).

Jazz musician Ryoichi Hattori attempted to produce Japanese native music which had a "flavor" of blues. He composed Noriko Awaya 's hit song "Wakare no Blues" (lit. "Farewell Blues"). Awaya became a famous popular singer and was called "Queen of Blues" in Japan. Due to pressure from the Imperial Army during the war, the performance of jazz music was temporarily halted in Japan. Hattori, who stayed in Shanghai at the end of the war, produced hit songs such as Shizuko Kasagi 's "Tokyo Boogie-Woogie" and Ichiro Fujiyama 's "Aoi Sanmyaku" (lit. "Blue Mountain Range"). Hattori later became known as the "Father of Japanese poppusu ". The United States soldiers—who were occupying Japan at the time—and the Far East Network introduced a number of new musical styles to the country. Boogie-woogie, Mambo, Blues, and Country music were performed by Japanese musicians for the American troops. Chiemi Eri 's cover song " Tennessee Waltz " (1952), Hibari Misora 's "Omatsuri Mambo" (1952), and Izumi Yukimura 's cover song " Till I Waltz Again with You " (1953) also became popular. Foreign musicians and groups, including JATP and Louis Armstrong, visited Japan to perform. In the mid-1950s, Jazz kissa (ジャズ喫茶, Jazu Kissa, literally "Jazz cafe") became a popular venue for live jazz music. Jazz had a large impact on Japanese poppusu, though "authentic" jazz did not become the mainstream genre of music in Japan. In the late 1950s and early 1960s, Japanese pop was polarized between urban kayō and modern enka.

Modern J-pop is also sometimes believed to have had its roots with Chinese immigrant jazz musicians who had fled Shanghai during the communist takeover, and were collaborating with American soldiers to help introduce a variety of new genres to the Japanese public. In 1949, when the communists took over and established the People's Republic of China on the mainland, one of the first actions taken by the government was to denounce popular music (specifically both Chinese pop music, known as Mandopop, and Western pop music) as decadent music, and for decades afterwards the Communist Party would promote Chinese revolutionary songs while suppressing Chinese folk songs, Chinese pop songs and Western pop songs. Dissatisfied with Chairman Mao Zedong 's new music policies, a number of Shanghainese jazz musicians fled to the British colony of Hong Kong and established Cantopop, which is pop music sung in the Cantonese dialect of Chinese. However, a few musicians instead settled in Japan, where they became members of the Far East Network and collaborated with the American soldiers to help expose the Japanese public to a wide variety of western genres. This eventually lead to the establishment of modern Japanese pop music, known as kayōkyoku.