Naoko was born in Nagoya, Japan and moved to New York with her parents when she was four before returning to Japan, then relocating to London when she was 12. She began to take singing lessons, and at 17 she was cast in the lead role of Kim in the West End musical "Miss Saigon" opposite John Barrowman, with whom she would later appear in the TV science-fiction series "Torchwood." She has appeared on television as Julia Sawalha's studious friend Sarah in "Absolutely Fabulous", the hospital reception in "Casualty", and Yoko Ono in "Lennon Naked." In 2006 she returned to the London musical stage to play Christmas Eve in "Avenue Q," and in 2015 she was part of the huge ensemble cast in the big-screen "Everest" as ill-fated mountaineer Yasuko Namba.