Commonly known just as Ayu, Ayumi Hamasaki is one of the most popular and influential Japanese pop singers in Japanese music history, and is dubbed "the Empress of J-Pop".

Since her debut in 1998 with her first single "poker face", she has sold more than 46 million copies, with the releases of her seven full-length studio albums, one mini-album, two compilation albums, 40 singles, and several non-studio albums, being the fourth top selling Japanese artist in the history of Japan. With the release of BLUE BIRD, Hamasaki's single sales have passed the 20 million mark, making her the first solo and female singer to do so.

(taken from wikipedia)