Rainbow is a Fairilu. She has pale skin and cheek spots on her face. Her eyes are blue and her ears are pointed long. Her hair is very long and curvy with her forehead visible through her middle-parted hairline. Her hair is multicolored with gradients of yellow, pink, and blue. Her wings are colored light-blue.
Her apparel consists of a pink prom-like sleeveless dress. She wears wrist straps on her wrists and has two pink bows, one on her right chest and one on the top of her hair. She wears pink heeled pumps as her only footwear.
Her Fairilu Key is colored pink with a star-shaped handle and a blue jewel decorated in its center.
In Tell Me, Magical Pendulum, her hair has vivider colours. Her shoes has also changed colour to blue.
- Rainbow's name is based on the meteorological phenomenon rainbow. It is when the sun is visible in the sky producing light rays, then there is patch of rain that precipitates in a given area. The result is a prismatic light diffraction that produces a rainbow of the colors in the sky.