Haikei Heika, Nidome no Ouhii wa Okotowari!

Alicia, the daughter of a duke, was to become the second queen of the young king. After the sudden deaths of the king and his wife, the throne is inherited by their younger brother, Julian. She agrees to remain in the kingdom until it is stable, but Julian, though polite, has ulterior motives and intends to marry her.