[2] Koga was born in 1904 in the village of Taguchi (today part of the city Ōkawa) in the Mizuma District of Fukuoka Prefecture; he was the sixth of eight children.

During this period, Koga was gifted a taishōgoto from his cousin; then later, while enrolled at the Keijō Good Neighbor Trade School, a mandolin from an older brother living in Osaka.

[3] He was regarded as a notable figure for establishing the genre enka, though Koga considered that he was a ryūkōka composer.

Koga’s songs have been heard by Western audiences in various films, including Come See the Paradise, and Memoirs of a Geisha.

A museum was built in Shibuya to honor his achievements, and visitors to the Koga Masao Museum of Music (古賀政男音楽博物館, Koga Masao Ongaku Hakubutsukan) are able to view exhibits, and memorabilia featuring his work.