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…

由香與誠是同班同學，他們同時來自單親家庭。某天，他們正在萌芽的愛情，因為雙方父母的結合而起了重大的變化。這時，誠的補習老師惠裡子出現，更令事情一發不可收拾……….純一與妹妹互相傾慕，但礙於近親關憬只好埋在心坎裡。一次意外令惠裡子喪失記憶，甚至連純一也全無印象。純一決定將他們的兄妹關係隱瞞，二人更因此熱戀起來…..劇中兩女和數男發生多次性事，最後她們的選擇是明確的。