Mew Fumizuki is an alien android dispatched to Earth with her partner, Mica Minazuki, on a mission to defend the planet from external threats. She operates under the command of a slug-like superior. Her physical appearance features short blue hair and striking cyan eyes. To blend into human society, she adopts the identity of a typical high school student named Miyu Fumizuki, concealing her true nature as the combat-ready Hyper Doll.

Her personality is quieter and significantly more laid-back than Mica's. Mew often displays a strong reluctance to engage in superhero duties, prioritizing leisure activities like eating ice cream or attending festivals over responding to crises unless compelled by direct orders from their commander.

Her relationship with fellow Hyper Doll Mica involves frequent arguments and interpersonal conflict, hindering their teamwork; their interactions are characterized by mutual irritation rather than cooperation. The sole human aware of their secret identities is their classmate, Hideo Akai. After his accidental discovery, Mew and Mica repeatedly threaten him with physical violence, warning to "twist his head off" or expose him to extreme danger to ensure his silence, as their operational parameters forbid killing humans.

In combat, Mew exhibits formidable capabilities including flight, superhuman strength, and near invulnerability. However, her participation is typically half-hearted and frequently results in significant collateral damage to the surrounding environment, coupled with general apathy toward the consequences. Her off-duty demeanor includes subtly robotic speech and behavior, hinting at her artificial origins and underlying detachment from human social norms despite her human disguise. Her portrayal remains consistent as an apathetic and reluctantly powerful entity throughout her appearances.