Rihoko Nagao is a Japanese voice actress born on November 14, 1964, in Kanagawa Prefecture, Japan. Her career in the anime industry was primarily active during the late 1980s and 1990s. She was formerly affiliated with the talent management agency Arts Vision and later with Office Tokuhiro.

Nagao is known for her voice roles in several original video animation projects from this period. One of her most recognized performances is as Yuka Nakamura in the 1990 OVA series 1+2=Paradise. This two-episode series, based on a manga, features Nagao voicing the younger of the twin Nakamura sisters who are central to the story. She also voiced the character Gozen Ijuusan in the 1991 OVA Ore no Sora Keiji Hen. Her other anime credits include a role as Kurumi in the television series Tsurupika Hagemaru-kun, which aired in 1988, and a part in the 1986 animated film Project A-ko, where she is credited with voicing a character in a couple.