Rasati is Lillia's older sister and a talented martial artist that regularly participates in tournaments against Edel Raid Pleasures (and still manages to defeat them without an Edel Raid of her own). She is extremely protective of Lillia, and because her sister is an Edel Raid, she looks down upon Pleasures for using them as "weapons". She instead relies on Ki-based attacks and pure determination. Rasati is also very tomboyish and usually serious.
Lillia, being an Edel Raid, was bought by the arena manager from Rasati's uncle. Realizing that paying back the debt would set the sisters free, Rasati became a determined fighter, putting all her winning money into paying off Lillia's debt.
In the anime, she is mainly around just for the arena arc with some less important roles later. In the manga, the sisters continue to travel with the main group for quite some time.