Miana belongs to the Houtua tribe, a descendant group of humans who remained on Earth after humanity's exodus. She serves alongside her twin sister Maina as a priestess, communicating with the egg of their fallen deity Mothra. Her primary role involves safeguarding tribal traditions and interpreting spiritual guidance through telepathic connections linked to the egg.

Physically, Miana stands approximately 150 centimeters tall. She possesses white hair resembling feathers, green eyes, and a tanned complexion. Distinctive white and dark red tribal markings cover her body, secreting healing scales. Her traditional Houtua attire consists of a blue top, dark red skirt, blue pants, and brown sandals. A key distinguishing trait from her sister is her consistently docile facial expression.

Her personality exhibits curiosity, gentleness, and empathy. Initial encounters reveal wariness toward outsiders, startling and fleeing when Haruo Sakaki awakens in her hut. Yet, she demonstrates compassion by rescuing him and treating his injuries with medicinal powder derived from her scales. She gradually develops trust in Haruo, learning human language through exposure and showing concern for his safety, contrasting with Maina's more confrontational demeanor.

During events in Tanzawa Forest, she tracks United Earth forces and later saves Haruo from hazardous marshlands by telepathically warning him of predatory worm-like Servum. She assists captured survivors by facilitating telepathic communication between Houtua elders and humans. Insisting on accompanying Haruo's mission to locate Mechagodzilla City alongside Maina, she guides them to the site while cautioning that its nanometal composition is "sinister" and "poison."

Critical moments include witnessing Haruo share a kiss with Yuko Tani; her expression reveals dismay, suggesting developing romantic feelings. During Godzilla Earth's assault on Mechagodzilla City, she and Maina telepathically alert Haruo to evade atomic breath attacks. Later, she confronts Exif archbishop Metphies after sensing his concealed telepathic abilities, leading to her capture. Metphies crucifies her as an offering to summon Ghidorah, though she psychically screams the monster's name to alert Haruo before losing consciousness.

Following Ghidorah's defeat, she participates in tribal ceremonies, including officiating Haruo and Maina's wedding. In subsequent months, she observes Haruo's emotional decline after Maina's pregnancy and Yuko's nanometal-induced coma. She attempts to dissuade him from suicidal vengeance against Godzilla, invoking Houtua philosophy that survival constitutes victory. Her final plea emphasizes their cultural absence of the concept "hate," framing Godzilla as a natural force akin to storms. She fails to prevent his self-destruction, symbolizing the collision between tribal acceptance and human vengeance.

Her abilities encompass telepathic communication, environmental precognition (detecting threats like marsh creatures), rapid language acquisition, and combat proficiency with nanometal-tipped arrows capable of piercing Servum hides and spacecraft armor. The healing properties of her biological scales also provide limited resistance to nanometal assimilation.

Relationships define key narrative aspects: her inseparable bond with Maina reflects synchronized actions in combat and guidance; her protective dynamic with Haruo evolves from rescue to unreciprocated affection; and her skepticism toward Metphies exposes tribal distrust of external influences. Tribal elder Munak mentors her spiritual interpretations, while tensions with Yuko illustrate cross-cultural misunderstandings.