Five years ago Kyousuke's wife Shouko left him for another man and sent divorce papers from a foreign land leaving him to raise their four daughters alone. Now he works as a janitor at the high school his daughters attend and looks after them every day. Suddenly a relative's daughter comes to live with the four girls and their father. Since she is older than all of them they are worried that she may become a candidate for their new mother. So instead they position themselves to take the roll of the new mother and wife of their father.