Marmalade Boy begins when Miki Koishikawa's parents decided to go to Hawaii. They fell in love again with another couple by the name of "Matsuura" and decided to exchange partners with them. Miki was informed by her parents that they would be getting a divorce and marry again. She also learned that the couple her parents were intending to exchange partners with had a son named Yuu Matsuura.
Now, not only does Miki have to deal with two sets of parents but her sudden feelings for Yuu.....
