She was born and raised in Niihama, Ehime, Japan, Mizuki was trained as an enka singer. She made her debut as a voice actress in 1998; however, she released her debut single "Omoi", under the King Records label on December 6, 2000. A year later, she released her debut album, Supersonic Girl on December 5, 2001.
In the years that followed, Mizuki enjoyed modest success that concluded with the release of her single "Innocent Starter", which reached the top 10 Oricon singles chart, charting at No. 9. Since then, Mizuki's releases have charted steadily higher in Japan, establishing her as a successful singer in the country. Despite this, she remains a prolific voice actress, with over 130 voice roles in separate media. On June 3, 2009, her album Ultimate Diamond reached #1, her first release to do so; while her single "Phantom Minds", released on January 13, 2010, also charted at #1. Mizuki is the first voice actress to top the weekly Oricon albums chart and the weekly Oricon singles chart since its inception in 1968.