Marmalade Boy [Manga]

Rumi and Jin Koishikawa unexpectedly announce to their daughter, Miki, that they are going to get divorced. Not only that, but they plan to swap partners with another couple, Chiyako and Youji Matsuura (who have a son, Yuu, the same age as Miki), and get re-married. The families move in together, and a romance develops between Miki and Yuu. Various romantic triangles start to appear, and quite a few people try to break Miki and Yuu apart. Yuu is also searching for the identity of his biological father and confesses his frustrations to Miki. Their romantic relationship continues to thrive and, despite all obstacles, they are together in the end.