Kizoku kara Shomin ni Natta node, Konyaku wo Kaishou saremashita! When I Became a Commoner, They Broke Off Our Engagement!

Synopsis

Thirteen-year-old Anna was raised in a noble household, yet she looks nothing like the rest of her family and lacks her lineage's aptitude for magic. There's a very good reason for that, though—a mischievous fairy switched her with another baby at birth! When this detail comes to light, Anna's family kicks her out and ends her long-standing engagement to Edmund, a young nobleman who has always treated her with disdain. With her sheltered, privileged days behind her, how will Anna learn to adapt to life as a commoner with her new family? (Source: Yen Press)