Seo Yoona had a nice life, coming from a wealthy family, she got everything she wanted, but what she wanted more than anything was to be with her sister, Aria. Aria and Yoona were very close until the news of Aria's high IQ. Soon afterwards they started drifting apart. On Aria's 10th birthday, she got her parents to mistake her sister's birthday for hers, and got away with it. After this happening she felt really bad and made her cupcakes. Aria rejected her, this being the final straw of their friendship. Yoona got upset and this, and they haven't talked to each other much sense then.
Yoona is a little spoiled, but very cheery and sometimes pretty loud. Yoona can easily voice her opinions and is not afraid to say them. Yoona also has a good sense of humor, and can be funny when she wants to.
Super Speed: Seo Yoona has the ability to move, react, heal and think at very high speeds. For example, if she knows how to do a math problem, she can solve it faster than most people. She also has high stamania levels that can keep her going faster for longing.
Thermonuclear Body Blast: This power gives Yoona the ability to generate enough heat for herself and then being able to combine all of the heat to blast somebody unconscious.