Juliette is a supporting character who appears alongside her counterpart, Romeo. She is a female lamp post-shaped mechanical servant, sharing an identical design aesthetic to Romeo. Her background is directly tied to that of the cyclops aliens, a race of one-eyed beings who are the primary antagonists in the episode that introduces her. Juliette and Romeo were both originally servants and slaves to these aliens. At some point prior to the main events of the series, the pair fell from space to Earth together during what is described as a collapse in space-time.

In terms of personality, Juliette is depicted as being very optimistic, regardless of the circumstances she finds herself in. While the aliens she once served are brutal and aggressive, she and Romeo share a more neutral and cheerful disposition. However, like Romeo, she is sometimes portrayed as having a mischievous or less than entirely helpful side, as they are both known to engage in chaotic behavior, such as firing bullets while playing games or causing trouble for other characters, fitting the series' brand of comedic violence.

Juliette's primary motivation is her relationship with Romeo, who is identified as her lover and later her husband. Her role in the story is almost entirely defined by this partnership. The two are introduced as a pair of alien robot lovers who are separated after falling to Earth. Her key storyline involves being rescued alongside Romeo. The protagonists, led by the cyborg cat Kuro-chan, encounter her inside a pyramid located behind a school, where she is held captive by the underground aliens. Upon being freed by Kuro and his friends, she regains her freedom and is reunited with Romeo. This rescue effectively concludes her servitude, allowing her to live freely on Earth. Juliette does not possess unique or specialized combat abilities that are highlighted as distinct from Romeo. As a mechanical being, she presumably has the structural durability and basic physical functions of her design, but her narrative function is not tied to her power level. Her most notable ability is enduring the chaotic adventures alongside Romeo with a consistently optimistic attitude. Following her liberation, her development is marked by the progression of her romantic relationship, as she and Romeo eventually marry and have a child together.