- Alias: Agatsuma Rumi (我妻ルミ)
- Birthdate: July 25, 1968
- Birthplace: Sendai, Miyagi Prefecture
- Blood Type: O
- Height: 154cm
- Sizes: 78 - 55 - 78 cm
- Sibling: Serizawa Naomi
Agatsuma Kayo joined Onyanko Club on January 23, 1987, becoming the 48th member. At that time, her sister was also an idol and was releasing her own records and appearing on shows. She debuted as a solo singer after Onyanko Club broke up on October 1987 with the single "Private wa Dangerous".
She got married on April 1989 and retired from show business for a short while. After her divorce in 1996, she came back on various television and radio programs.
- [1988.04.21] OH! CHAPPY
- [1988.12.01] Merry! Go Round
- [2003.12.03] Idol Miracle Bible Series Agatsuma Kayo 48 (アイドルミラクルバイブルシリーズ 我妻佳代 48)
- [1987.11.21] Private wa Dangerous (プライベートはデンジャラス)
- [1988.03.21] Hitoshi Yubi no Wiper (ひとさし指のワイパー)
- [1988.07.21] Sekirara de Ikou! (Seキララで行こう!)
- [1988.10.21] Kanashimi no Mukougawa (悲しみの向こうがわ)
- [1988.04] KAYO AGATSUMA
- "我妻佳代". Japanese Wikipedia: 我妻佳代. 2005-10-13. Retrieved 2012-07-31.