Mizuno was active in drama club in high school, playing the heroine in the annual play three years in a row. She made her film debut at Shochiku in 1957. She also acted in films for Toho, but unlike most of her colleagues she was not under an exclusive contract.

Mizuno is popular among genre fans for her bewitching looks, especially in films such as Matango (1963), Monster Zero (1965), and Godzilla vs. the Sea Monster (1966, of MST3K fame). Her American co-star from Monster Zero, Nick Adams, was rumored to have had an affair with her, and he allegedly asked her to marry him. She enjoyed appearing in sci-fi, and appeared in two of the Millennium Godzilla films, including the 50th anniversary film Godzilla: Final Wars (2004).