From MangaHelpers:
It was a weird feeling for Saki when she received an inheritance from a father whom she had never even met before. And it got even more odd when she was required to live in a house away from her grandparents for a short while. But what topped off the cake was when Saki found out her roommates were going to be four other girls, all daughters of her father from different mothers, which made them all half sisters. They all range in age from the youngest at elementary school to the oldest already in college. From going to the only child to living in the house with four new sisters is going to be a new experience for Saki, but she is warming up to the idea of having sisterly bonds.