Ritsuko Kasai is a Japanese voice actress born on December 18, 1971, in Hokkaido, Japan. Her career in anime spans from the mid-1990s through the mid-2000s, with her known roles concentrated in this period.

She is recognized for several supporting character performances in anime television series and original video animations. Kasai provided the voice for Hinata Okano, the supportive younger sister of the protagonist, in the 2004 television series Wind: A Breath of Heart, a role she also reprised for the OVA adaptation of the same series. Another of her notable roles is Misa Kuroki in the 1999 romantic comedy series Iketeru Futari. She also voiced the character Shiro in the 1997 adventure series Fortune Quest L.

Beyond these roles, her voice acting credits include appearances in a variety of other productions. She had a minor role in the acclaimed fantasy series Berserk (1997), voicing court ladies and maids in several episodes. Her other anime credits include Dokkiri Doctor, Case Closed, and the 2002 animated short film Noiseman Sound Insect. A Japanese-language database of her work lists additional voice roles in the 1998 television series Super Doll Licca-chan and the 1996 project Alice in Cyberland, as well as credits under various pseudonyms.

Kasai has also worked under a number of different aliases throughout her career, including 藤森りお (Rio Fujimori), 阿谷ほのか (Honoka Aya), 春日恵美 (Emi Kasuga), 高尾恭子 (Kyoko Takao), 倉見つくし (Tsukushi Kurami), 宫内裕香 (Yuka Miyauchi), 加仁礼, and まりあ (Maria). Her personal interests and skills, as noted in an encyclopedia of voice actors, include playing the clarinet and flamenco dancing.