Originally a daughter of a fallen noble upon being saved by Itsuki, which led to her extreme devotion to him. Upon entering his party she was at the lowest position of the hierarchy and tried to forcefully acquire power against her original potential ruining her growth. After being framed she became suicidal and was then saved by Naofumi, she then seeks new strength to return to Itsuki's side, but remains nervous in the presence of others, using the expression "Fuee" whenever startled or nervous.
Risha scares easily and she is a klutz.
Rishia was a fallen noble who even had to sell herself into slavery for the sake of money. And the one who saved her from such despair was Itsuki. He became her goal. Her aspiration. Though she did lose to it once and jumped into the ocean, you could also say that she had enough willpower to do such a thing.