Diane Martin is an FBI agent who joined Battle Fever to avenge her father, Special Agent Bosner, after he was murdered at Tokyo Airport by an assassin of Egos. She also has a sister named Catherine.

Serving as the original Miss America, she is armed with throwing knives and carries a Command Bat, while performing a distinct disco-style dance during the team's roll call.

After being severely wounded by the Dracula Monster, she returned to the United States in Episode 24, passing the mantle to Maria Nagisa. Diane officially appears as part of the team from Episode 1 to Episode 24.