Akeno Myōjō acts as Astrea's human alias, a central antagonist in Shinkalion Z. This cheerful, determined, and seemingly ignorant persona serves as a reconnaissance tool for her brother, Kannagi, within human society.

In her true form as Astrea, she enforces strict loyalty to the Teoti cause, using threats to suppress dissent among subordinates like Sougyoku and Zagan, instilling fear to ensure compliance. This stern exterior contrasts sharply with her deep loyalty to family, especially Kannagi and her late father. She exhibits visible grief upon her father's death and profound desperation when Kannagi loses control due to forbidden code. In this crisis, she abandons pride to plead with former underling Abuto Usui for help and later offers her own life to Camalus and Bahram in exchange for Kannagi's safety.

Astrea initially shares Kannagi's belief that coexistence between their species and humanity is impossible. However, after witnessing Kannagi's change of heart and recognizing flaws in their ideology, she undergoes significant development. She abandons her antagonistic stance, adopting a cooperative and friendly attitude toward former enemies.

As a member of her species, she is the only named female. Although older than Kannagi, cultural precedents within their hierarchy result in him inheriting the Teoti monarch title after their father's death, a deviation from typical royal succession norms.