A very spaced-out and slow-tempo girl, Shi Yoon is one of the girls who came abroad from Korea to study the art of Prism Shows at the Pretty Top agency. She is one of the members of the Prism Show unit, PURETTY. She is the all-noticing, thoughtful big sister role of her team. Usually, she is very kind and docile, but she is actually extremely scary when angered. Her best friend in Prizzmy☆ is Karin. Her catchphrase is "Ya~y!"