Nigashita Sakana wa Ookikatta ga Tsuriageta Sakana ga Ookisugita Ken

From a very young age, people noticed that Maria, the youngest daughter of a duke, was filled with potential. She was raised as the heiress of her house, until the birth of her baby brother relieves her of her duties. She scrambles to find a husband, but all the eligible bachelors in her duchy are taken! At this rate, she's doomed to the life of a spinster!