Namikawa was selected by the Controller of Planet X to travel to Earth to prepare for the Xiliens' planned invasion. Namikawa posed as the CEO of a Japanese educational toy company, which was used as a cover to purchase the rights to a device created by inventor Tetsuo Teri, which could produce a sound that is lethal to the Xiliens. During this time, Namikawa became romantically involved with Glenn, an American astronaut in Japan working on a joint American-Japanese space mission to explore Planet X. While at first her relationship with Glenn was meant to be a ruse to keep Glenn in the dark as to the Xiliens' true intentions and provide her commanders with additional information about the Earthlings, Namikawa began to feel true romantic feelings for Glenn.
During his second visit to Planet X, Glenn saw some of the Xilien women, and noticed that they were all identical to Namikawa. Upon returning to Earth, where the Xiliens had just begun their siege, Glenn found and confronted Namikawa, now aware that she was an Xilien agent. Namikawa confessed to Glenn that she in fact truly loved him, and that they could live happily together if he came with her back to Planet X and married her. An Xilien patrol found Glenn and Namikawa together, then killed Namikawa and took Glenn prisoner, stating that love was against the protocol ordered by the computer that ran the Xiliens' lives. Despite her death, however, she managed to give Glenn a letter explaining to him that the sound emitted by Tetsuo's Lady Guard alarm was lethal to her race, allowing humanity to defeat the Xiliens.
- In Godzilla: Final Wars, there is a character named Akiko Namikawa, also played by Kumi Mizuno, who is at one point impersonated by an Xilien.