Keiko Yamazaki operates within a freelance detective agency team alongside Junpei, Akira, and Kumiko. She functions as the team's well-connected tech specialist, managing all technology-related tasks during investigations. Her expertise proves vital when the team acquires a sensitive floppy disk containing advanced weapon schematics from a dying engineer.

Keiko maintains composure during dangerous situations, including confrontations with a corporation determined to recover the disk. After Kumiko is kidnapped by the corporation's operatives, Keiko participates in the rescue efforts. This requires navigating threats posed by the corporation's experimental military technology, such as an assault robot.