Eiko Anzai operates as a Mobile Rescue Police operator, characterized by olive hair in a ponytail with face-framing chin-length strands and grey eyes. Her standard uniform includes a white shirt with a red tie, a blue jacket bearing a golden "DH" badge, and a dark blue skirt.

Personality-wise, she exhibits dedication to operational support while occasionally revealing inexperience and uncertainty in her duties. She works jointly with fellow operator Megumi Shinmon.

During an Evil AI takeover of headquarters, she aided Shinmon and Arisa Munakata in manually blasting open a door to enable Drive Heads deployment. Later, when Evil AI duplicates attacked the facility, Commander Takahito Saionji tasked her with civilian evacuation efforts during a tour. Facing imminent danger, she was shielded by Shun Kuroeda piloting the S.I.B. Max. In the final battle against the supercomputer Ark, she monitored combat progress from the command room.

She performs duties in the command room alongside Shinmon during the feature film's events and appears in the ONA series continuation.

Her surname Anzai combines the characters for "peace" and "equal"; her given name Eiko uses those for "reflection" and "child."