Miana appears across the Godzilla anime trilogy as a member of the Houtua tribe, descendants of humans who stayed on Earth. Alongside her twin sister Maina, she serves as a shrine maiden tasked with protecting a sacred egg tied to their fallen deity. Her tribal designation is "Baby Chick".

She possesses white feather-like hair, green eyes, and a tanned complexion marked by distinctive white paint designs on her face and body. Her attire consists of light fabric clothing, brown sandals, and a face-concealing mask.

Personality-wise, Miana displays greater curiosity and openness than her reserved sister. She exhibits inquisitiveness towards human technology and newcomers, expressing herself less aggressively. This distinction helps Haruo Sakaki tell the twins apart.

Her narrative begins when she observes Haruo and his companions returning to Earth. Startled by Haruo, she flees, but later rescues him from swampy terrain after an attack by Godzilla Earth. She struggles to pronounce his name, fragmenting it as "Ha. Ru. Oi". She guides Haruo to other survivors and participates in telepathic communications between the Houtua and humans concerning intentions and destructive landing bombings.

Miana actively joins the mission to locate Mechagodzilla, saving Yuko Tani from Servum creatures using nanometal arrows. She voices distrust towards Mechagodzilla City, calling it sinister and poisonous before temporarily departing with her tribe. Later, she witnesses Haruo and Yuko kissing, reacting with a visibly downtrodden expression suggesting potential romantic feelings for Haruo.

In the concluding events, she agrees to help protect Haruo from Metphies. Seeing his despair over Yuko's condition and his failure against Godzilla Earth, she offers philosophical comfort, explaining the Houtua belief that survival and "connecting life" constitute victory against invincible monsters. She attempts to physically express this connection by undressing and propositioning Haruo, but he gently declines.

Confronting Metphies over his psychic abilities and machinations, she uncovers his intentions before being captured. Metphies shows her a vision of Ghidorah, rendering her unconscious. She is crucified as an offering to the Exif god. Before losing consciousness completely, she psychically screams Ghidorah's name, alerting Haruo and Maina to her plight.

Following Ghidorah's defeat, she is rescued and participates in officiating the wedding between Maina and Haruo. As human survivors integrate into Houtua society, she attempts to uplift Haruo by showing him the first spring flowers. Sensing his turmoil when he retrieves Yuko's body, she confronts him, recognizing his intent to die alongside Yuko. She berates him for choosing defeat, declaring "That's losing!" before he proceeds with his final act.

Her capabilities include telepathic communication, limited precognition, radiation resistance, and combat proficiency using nanometal arrows capable of killing Servum and penetrating spacecraft armor. She demonstrates superhuman speed, stamina, and acrobatic skills in combat and traversal.

A manga adaptation shows her tending to an injured Haruo after Godzilla Earth's initial attack. She and Maina are considered narrative adaptations of the Shobijin characters from earlier Godzilla lore.