Mitsuki Aoyagi, who fights as Akiba Blue, is an eighteen year old martial artist with a serious and cynical disposition. She is recruited into the Akibarangers specifically because of her combat proficiency, and her initial motivation for joining is a desire to improve her fighting skills. Unlike her teammates, Mitsuki has little to no knowledge of Super Sentai at the outset, and she is visibly uncomfortable with the team's ritualistic poses and the practice of addressing one another by color-coded code names rather than real names. Her reluctance fades over time; she eventually warms to sentai culture after spending a day watching episodes of GoGo Sentai Boukenger and gaining inspiration from veteran action director Kazuo Niibori. This leads her to develop her own distinctive roll call and commit more fully to the team's mission.

Despite her outwardly serious demeanor, Mitsuki harbors a secret fondness for the in‑universe anime Nijiyome Academy Z‑Cune Aoi, a fact she keeps hidden from her comrades. This private enthusiasm contrasts with her usual blunt and sometimes harsh attitude, particularly toward the eager and otaku‑driven Nobuo Akagi. Her seriousness can make her seem insensitive, but it also grounds the group and provides a counterbalance to the more flamboyant personalities around her.

Mitsuki’s role on the team is that of the pragmatic, combat‑focused member. Her martial arts background makes her a formidable fighter even before transformation, and as Akiba Blue she channels her physical skills through the MMZ‑01 transformation device, employing the standard arsenal of the Akibarangers including the Moe Magnum finisher. She does not possess any unique superhuman abilities beyond those granted by the Akibaranger gear; her strength lies in her disciplined training and no‑nonsense approach to battle.

In terms of relationships, Mitsuki is initially distant from Nobuo Akagi, often dismissing his sentai‑centric enthusiasm, but she develops a grudging respect for his knowledge and leadership over the course of the first season. She bonds more closely with Yumeria Moegi, though their contrasting personalities still create occasional friction. Her relationship with the team’s commander, Hiroyo Hakase, is professional and cooperative.

Mitsuki undergoes a clear arc from reluctant participant to a warrior who embraces her role, even seeking official recognition. After the events of the first season, the timeline is altered due to a retcon; in the revised continuity she is scouted by the Pentagon and leaves for the United States, making way for a new Akiba Blue in the second season. This departure marks the end of her direct involvement with the Akibarangers.

Notable abilities include her advanced karate skills, which she demonstrates both in and out of costume, and her eventual mastery of the Akibaranger’s transformation and combat mechanics. She does not wield any special superpowers beyond the standard delusion‑based technology of the team.