19-year Segawa Yuuta was looking forward to start his new university life and go through a normal university life, making new friends, etc, etc. But suddenly, when the plane which his elder sister and brother-in-law were on went missing, he became the 'father' of his three young nieces! Now, his six-tatami mat apartment not just has to accommodate himself, but 14-year old Sora, 10-year old Miu, and 3-year old Hina. What will be the fate of Yuuta?