Born as Sachiko Kamachi, known professionally as Izumi Sakai (I opted for this name for the tag since she was mostly well-known as such, hope is not a problem), was a Japanese pop singer, songwriter, and member of the group Zard. One of the the best-selling female recording artist of the '90s as well as best-selling music artists in Japan of all time, she was also a recurrent composer for Japanese animated series and movies (prominently Detective Conan). A very prolific song-writer, too.
She passed away in May 27, 2007.
And I just want to add that, as a fervent Dragon Ball fan, I hold her very close to my heart. ♡