When production of You Only Live Twice began, Wakabayashi was originally slated to play the role of Kissy Suzuki whilst her co-star Mie Hama played Suki, one of Tiger Tanaka's top agents. When learning English proved to be a major hurdle to Hama, the women switched roles, with Hama now playing the smaller part of Kissy and Wakabayashi playing the larger part of Suki. At her suggestion, the character of Suki was renamed Aki. They had previously acted together in King Kong vs. Godzilla (1962) and Kokusai himitsu keisatsu: Kagi no kagi (1965).

She is best known in English-speaking countries for her role as Bond girl Aki in the 1967 James Bond movie You Only Live Twice. Before this, she had made many movies in her native Japan, especially Toho Studio's Monster movies, such as Dagora, the Space Monster (1964) and Ghidorah, the Three-Headed Monster (1964), both of which were also released under various other titles. In Gidorah, she played a mystical Princess, who could predict the Future and was also a prophetess.

In 1971 she made an appearance in an episode of Shirley's World. Wakabayashi made only one more film (and a guest TV appearance) before disappearing from both the big and small screen. In an interview in G-FAN magazine (No. 76), Wakabayashi said she retired from acting owing to injuries sustained while making a movie.