A-ko seems to be near invulnerable with superhuman speed and strength, is the heroine of the series and lives in Graviton City, Japan. A-ko is usually very friendly, cheerful, and polite, and always tries to lead a normal life despite her unusual lineage. However, she does have a fiery temper, and is very dangerous when angered. She has a large appetite, and a tendency to oversleep on school days. Her constant friend is C-ko Kotobuki, whom she has known since kindergarten. Although she truly loves C-ko, even she can be frustrated at her friend's relentless immaturity.

A-ko's powers are kept in check by the distinctive armbands that she always wears. Without them, her strength is uncontrollable, and she destroys nearly anything she touches (and even things that she doesn't touch.)

It's hinted that her mom and dad are Clark Kent and Diana Prince (Superman and Wonder Woman)