Keiko Iseki (井関佳子), now known as Yoshiko Iseki (same written form in Japanese), born January 19, 1970, in Kanagawa, Japan, is an actress who played Zirconia in the Sailor Moon musicals. Her first performance was in Sailor Moon SuperS - Yume Senshi - Ai - Eien ni... and her last musical was the Sailor Moon SuperS Special Musical Show.
- She is a vocalist and songwriter of the music group Nekomaji (ねこマジ).
Keiko performed as Zirconia in the following musicals:
- Sailor Moon SuperS - Yume Senshi - Ai - Eien ni...
- Sailor Moon SuperS - (Kaiteiban) Yume Senshi - Ai - Eien ni... Saturn Fukkatsu Hen
- Sailor Moon SuperS Special Musical Show