Akiko Narumi assumed leadership of the Narumi Detective Agency and Kamome Billiards Hall after her father Sokichi’s passing, relocating from Osaka to Fuuto unaware of his death until the Dummy Dopant incident revealed the truth. Balancing managerial duties with investigative work, she frequently clashes with colleague Shotaro Hidari over differing approaches, such as revamping the agency’s website with a vibrant, feminine flair.

Her playful, childlike exterior—marked by startled exclamations of "I didn’t hear about this!" and a signature green sandal used for comic discipline—belies keen deductive intuition, allowing her to crack cases that stymie others. She upholds her father’s protective ethos, fiercely advocating for clients’ safety.

Romantic entanglements intertwine with her professional life: her marriage to Ryu Terui, the covert police officer Kamen Rider Accel, weathered strains from his secretive work before solidifying during Movie War Core, where Sokichi’s spirit symbolically escorted her down the aisle. The couple later welcomed a daughter, Haruna, referenced in Drive Saga: Chaser.

Akiko actively engages in field investigations, briefly inhabiting Kamen Rider Double’s role during the Nightmare Dopant case to expose the antagonist and confronting threats like the Puppeteer and Money Dopants despite grave risks. Professionally, she retains her maiden name to honor Sokichi’s legacy, legally adopting Terui post-wedding. Her bond with Shotaro matured into a sibling dynamic, leading him to accompany her at her wedding in Sokichi’s stead. Spin-offs like Kamen Rider W Returns: Accel depict fleeting marital tensions over Ryu’s clandestine missions, swiftly resolved.

Across adaptations, including video games Kamen Rider: Memory of Heroez and Kamen Rider Travelers Record, Akiko remains a consistent blend of levity and capability, merging the agency’s traditional grit with contemporary accessibility.