Rinia is the elder daughter of Gyes, the warrior chief of the Dorudia Tribe. Due to her stupidity, her grandfather Gustav sent her to the Magic Ranoa Academy in order to gain knowledge; however, because of her linage as a royalty of the Beast Race, Rinia was treated with great care and became pampered. Rinia, along with Pursena, became arrogant and acted like delinquents.

(Source: Mushoku Tensei Wikia)