Yuka and Makoto study in the same school, they adore one another. One day, their parents announce their remarriage. They become brother and sister suddenly. Now they cannot get along as they wanted. Meanwhile, Makoto's tutor appears and affect their relationships. Since then the situation is only getting uncontrollable...Junichi is deeply in love with Eriko, but they are blood-related brother and sister. One day, an accident causes Eriko loses all her memories. Eriko even can't recognize Junichi. Junichi decides to hide their true relationship and begin dating with Eriko...