Reikoku Ou wa Hatsukoi ni Kuruu

Princess Sophia, born in exchange for her mother's life, has lived a life of oppression, having received an oracle of being a “Kingslayer” that will one day threaten the life of her father, the king. On the day the new king of a neighboring kingdom comes to greet her, she hears of her stepmother's plans to assassinate her... https://www.cmoa.jp/title/296331/