Crystal Kay debuted as a singer at 13 years of age in 1999 under Epic Records Japan.

In 2005, Crystal Kay sang the eponymous theme song for the Tsuyoshi Kusanagi drama Koi ni Ochitara: Boku no Seikō no Himitsu.

"Koi ni Ochitara" became Crystal Kay's most successful single, being certified for a million ringtone downloads.

[1] In March 2013 Crystal Kay relocated to New York City to pursue an American debut through Copetin Inc, releasing the single "Busy Doing Nothing" a year later.

In October 2014, Crystal Kay re-focused on Japan by switching her management to LDH.