Born in Adachi, Tokyo, Japan to a Japanese mother and British father, Kimura started working as a model in 2002 for the Japanese magazine Seventeen. She went on to host the morning television show Saku Saku from April 14, 2003 to March 31, 2006.

Kimura released her only indie single, titled "Level 42", but it was later released as her major label debut single on June 23, 2004, after she signed with Columbia Music Entertainment. The song was used over the end credits of Saku Saku. On October 27, Kimura released her second single, "Happiness!!!", which was followed by her debut album, Kaela, on December 8, 2004.