Rheta is the personification of the celestial body of the same name. They are the third planet from the sun and the only world with a majority native human population. In the past, they fought with their sister, Theia, for a place in the Solar System, resulting in the awakening of the Moon God and the birth of Lunos, Rheta's moon. Being the only survivor of their conflict and mourning the loss of her sister, Rheta buried Theia within her planet's core.

Rheta has an impulsive, happy-go-lucky attitude and acts as a caring older sibling figure to the younger Celestial Bodies in the system, especially towards Lunos, whom she took in as her brother. She loves her friends very much and is fascinated by her planet's inhabitants.