Yui is noted to be regal, kind, and caring. She shows a lot of compassion towards people and always wants to help. She is extremely brave and doesn't think twice when it comes to helping out or doing something that she thinks is needed. Yui has a natural sense of leadership and is able to easily strategize and keep people calm and collected. Though she is not quick to boast, nor does she think highly of herself that it seems vain. She has a comforting sense of confidence that follows her, and she is usually the person who always keeps her head held high.
Leaning towards the smaller side, Yui has great posture that makes her seem a bit taller. She has dark skin, long dark curly hair that falls to her back, and large pink eyes. Yui has a bit of muscle due to working out but has a slightly curvaceous body figure.
When at UA, Yui wears the standard UA uniform. When she is tinkering and inventing, she wears a pink tank top and sleeveless overalls as well as pink construction boots. Her casual wear consists of pastel pink outfits. She wears a gold bracelet and necklace, that she faithfully wears and never takes off.