Kōhaku Uta Gassen (紅白歌合戦, Kōhaku Uta Gassen), more commonly known as simply Kōhaku, is an annual music show on the New Year’s Eve. Literally “Red and White Song Battle,” the program divides the most popular music artists of the year into competing teams of red and white. The “red” team or akagumi (赤組, 紅組, akagumi?) is composed of all female artists (or groups with female vocals), while the “white” team or shirogumi (白組, shirogumi?) is all male (or groups with male vocals).
Further Reading: Anime/Manga Songs on New Year’s Kōhaku Uta Gassen (ANN)