Yuuyan is Erin's light brown-haired, brown-eyed classmate and roommate at the Kazalumu Beast Sanctuary, a place where students train to become beast doctors. She appears as a teenager. Yuuyan immediately befriends Erin upon her arrival. Her exuberant and inquisitive nature drives her to ask Erin numerous questions about her background and experiences. This enthusiasm springs from no longer being the sanctuary's only female student and a deep fascination with Erin's heritage from the Mist People (Ahlyo), despite the headmistress instructing others to disregard it.

Yuuyan's outgoing personality and lack of inhibition provide vital support, helping Erin navigate feelings of being an outsider. She shares her own experiences of facing initial skepticism due to her accent, framing such differences as inherent and positive aspects of individuality, aiding Erin's acceptance of her unique background.

A significant moment occurs when Yuuyan witnesses the Royal Beast Leelan bite Erin during molting season, causing severe wounds after Erin attempts to brush it. Yuuyan reacts with terror and rushes to assist Erin alongside their classmate Tomura.

Yuuyan also exhibits a shy side in romantic matters, harboring a crush on their classmate Kashugan while struggling to express her feelings to him directly.