Futami Nozomi is a 3rd-year middle-school student. After his mother passes away and his father is transferred abroad, he moves back to the town in which he was born, and begins to live in Sorinji Temple with relatives.
One of the factors motivating his return is the desire to renew his childhood friendship with twin Ichijou girls Sumireko and Kaoruko, who had both made a childish promise to marry him when they grew up.
Now, this particular town was home to a rather interesting legend. A sad tale about twin sisters who loved the same man. Although the man understood and shared their feelings, he was unable to choose between the two, and so ended up not making any choice at all. This legend is attributed to be the cause of the high occurrence of twins being born in the area.
So it is that Futami's life crosses paths with a total of 6 pairs of twins, all of whom develope a certain amount of affection for him.