I Abandoned My Engagement Because My Sister is a Tragic Heroine, but Somehow I Became Entangled with a Righteous Prince (Light Novel) Vol. 1

The light novel that inspired the manga! A saint under scrutiny is forced to live under the watchful eye of a justice-obsessed prince in this fantasy romance. Leia's life is turned upside down after her younger sister claims she's a cruel villain. Leia's fiancé breaks off their engagement, leaving her no choice but to throw herself into her saintly duties. But when confronted by the righteous Crown Prince Erik, she finds herself under his scrutiny. He's determined to suss out her true nature, but why does it involve living in the palace with him?!