Miana serves as a Houtua shrine maiden alongside her twin sister Maina, distinguished by white feather-like hair, green eyes, and a tanned complexion adorned with ritualistic white body paint. Her light fabric attire and face-concealing mask complement brown sandals revealed later. Contrasting Maina’s reserved demeanor, Miana exhibits curiosity toward outsiders, notably Haruo Sakaki, whose name she earnestly practices pronouncing. Her fascination extends to human technology, such as wrist displays, and she bridges cultural divides through proactive engagement.

Initially observing Haruo with caution, Miana grows emotionally invested after rescuing him from Mechagodzilla City’s destruction. Romantic feelings surface when her demeanor shifts upon witnessing his kiss with Yuko Tani. She later proposes a Houtua tradition of "connecting life" with Haruo—a bond intertwining survival and procreation—but faces gentle rejection. Her resolve leads her to confront Metphies upon detecting his telepathic pact with Ghidorah, resulting in her capture and symbolic crucifixion as an offering. During this ordeal, her psychic scream of Ghidorah’s name alerts Haruo and Maina, enabling her rescue.

Post-Ghidorah’s defeat, Miana officiates Haruo’s marriage to Maina, who carries his child. In the trilogy’s climax, she intuits Haruo’s plan to provoke Godzilla and destroy nanometal remnants, confronting him in a futile bid to prevent his sacrifice. Surviving his death, she witnesses Houtua-human integration and later shares a moment with Haruo’s memory, presenting spring flowers as a emblem of resilience.

Telepathically linked to Maina, Miana coordinates tribal defenses against Servum and Godzilla while communicating with survivors. The twins’ heritage subtly echoes the Shobijin, Mothra’s priestesses, though their lineage remains narratively unverified.