Ryuuichi is a university student. He used to live alone and enjoyed his school life. But one day, his apartment was destroyed by a fire... He reluctantly comes back to his house. But his house has been changed to a boarding house for girls...! It seems there is no place for him to live. But they all allow him to stay there together! His new life begins like this...

It's finals time, but tests aren't the only things stressing out Yuuta, who's literally being smothered with affection from his beautiful sisters: Chiyoko, who is feminine, caring, and coddles him; and Chinatsu, a strong-willed tomboy who desperately seeks his attention by picking on him. Who will triumph in this sibling love triangle?