Kunie Yoshiko is a doctor operating an ambulance. This ambulance is later revealed to be Guard Rescue, a disguised member of the Space Police Force. During her work, she encounters Yutaro Katori and grows suspicious of his true identity after repeated interactions. She accidentally discovers that Katori is the energy being Fighbird and simultaneously learns her ambulance is Guard Rescue. Yoshiko chooses to keep both revelations secret. Following this, she formally joins the Space Police Force as an honorary officer, actively participating in missions to protect Earth.

Her character exhibits compassion through her medical work and commitment to aiding others. A potential romantic subplot exists between Yoshiko and Katori, contrasting with reporter Momoko Yamasaki's infatuation with Fighbird. Yoshiko's feelings for Katori arise from observing his consistent kindness towards others, not solely his heroic deeds. This positions her as a grounded, sensible figure within the narrative.

In terms of appearance, Yoshiko typically wears her long hair tied in a bun during medical duties. In later story arcs, she is depicted with her hair down, consistent with her portrayal in the series' opening sequences. Her character development centers on transitioning from a medical professional to an involved ally of the Space Police, maintaining her dedication to helping others while adapting to extraordinary circumstances.