Podongpodonghan Yeojuneun Ingiga Eomnayo

The main character, stressed out from dieting and studying and decided to read the fantasy novel I Want to Be Ugly for Just One Day. She thought she would live a happy life as the daughter of a countess in the book, but the story turned out to be incredibly tedious... Our protagonist will try her best to change the original to make herself the happiest in the world, to protect her beloved family... Chubby will change history!

(Source: KakaoPage, translated)