This is one of the greatest anime comedy/love story ever.
10
Miki's ordinary life is turned upside-down when her parents suddenly announce that they are getting divorced in order to swap partners with a couple they met in Hawaii. They seek her approval of the change, telling her that they have arranged a dinner to meet the other couple, as well as their son who is about her age. At dinner, the adults share their plans of living all together in one big house and Miki reluctantly gives them permission. The other couple's son, Yuu, turns out to be fun and attractive, and Miki finds herself falling for him. Of course, it doesn't help matters when Yuu kisses her while she is pretending to be asleep in the nurses room at school. Little by little, Miki accepts her new family arrangement. At school, a long time classmate and former crush of Miki's, named Ginta, becomes jealous of Miki's new 'friend' and decides to try and gain her affections. He kisses Miki unexpectedly, for which he gets slapped. When Ginta later admits to Miki that he has loved her for years, and that his earlier rejection of her was a misunderstanding, Miki struggles between which of the two she wants to be with. Ginta tries to force Miki to choose between himself and Yuu. After a bit of indecision, Miki chooses Yuu. Yuu shares that he was the child of his mother and some man other than his father. Miki sympathizes with him and the two become boyfriend and girlfriend. As the series progresses Miki becomes very attached to Yuu...so much so that she is jealous whenever she sees another girl with him. It makes matters worse when his old girlfriend, Arimi, will do anything to get Yuu back. However, Miki has no reason to be jealous because Yuu is totally devoted to her. Meanwhile, Miki's best friend, Meiko is dealing with her own problems. She is seeing one of the teachers, who is affectionately referred to by the students as Na-chan. She loves him very much, but dating a teacher is taboo, and when they are caught, Na-chan resigns his position and leaves for Hiroshima. Meiko is depressed, but is encouraged by one of the seniors at school who likes her to write a story, and she ends up acclaimed as an author. After much hardship, her and Na-chan end up together again though. Miki later gets a part time job in order to help fund a trip with Yuu and one of her coworkers, Kei-kun, falls for her and tries to win her affections. At the same time, a cute model is trying to steal Yuu away from Miki. Yuu and Miki fight briefly, however, the two overcome all obstacles to stay together. As a result, their love for one another only grows stronger. Unexpectedly, Miki discovers that a transfer student from America, Michael, will be living with them for a while. He is attractive, and all the girls chase after him, however, he seems attached to Miki. Yuu suddenly decides to go to America to study architecture as an exchange student. Miki misses him terribly, and on top of that, she is pursued by both Kei-kun and Michael. Due to a misunderstanding, Miki is led to believe that Yuu is cheating on her. She flies to New York and the situation only gets worse. She decides that she is too lonely, and has turned into an awful person while having to wait for Yuu, so she breaks up with him. Back in Japan, Kei-kun and Michael force Miki to choose between them and she reluctantly starts dating Kei-kun. He treats her well and she is happy, but she still can't forget Yuu and feels lonely somehow. Yuu comes back to Japan for summer vacation and Miki is even more troubled. She cries when Kei-kun is about to kiss her, then tells him she is sorry. She runs off and makes up with Yuu. Back together again, their happiness is cut short when Yuu finds evidence that leads him to believe Miki is actually his sister. He breaks up with her and goes back to New York. Sad and unable to forget Yuu, Miki goes to New York to confront Yuu and he tells her she is his sister and they can't be together. Upset, Miki runs off and gets lost in Manhattan. She is bullied by a gang, but Yuu shows up and saves her just in time. The two decide that their love is too strong, and that even if they are siblings, they want to be together. At the airport, the rest of the family shows up because they were worried about Miki. Miki and Yuu confront their parents for not telling them they were siblings in the first place. The adults burst out laughing as they tell the couple that they have mistaken the situation and that they are not siblings after all. Yuu is really his fathers son, not another man's. The two are relieved and happy. Meiko marries Na-chan. They all live happily ever after...
