Zoya is the russian daughter of Euna or most often known as "The Princess Who Never Smiled" from the faiytale by Alexander Afanasyev with the same name.
Zoya is a king 15 year old girl who has to keep all positive feelings inside and try to make a good impression on her fellow fairytale characters. She is often holding the sides of her mouth to stop herself from letting out a giggle or to stop herself from smiling due to wide variety of pranksters at the school.
She is more often than not nice towards all the students, yet most may think she is being sarcastic due to her not letting her mouth curl up into a smile. She doesn't have many friends due to the fact most believe she is boring yet she remains true to the school and is loyal to her destiny, which is why there's the fuss of keeping her mouth from grinning and her vocal cords from vibrating at a large speed.