Marmalade boy was a drama about about two sets of parents getting a divorce, and swaping partners. When their the son (yuu) and daughter (miki) of both couple meet each other, they fall in love, however the anime countinues on with rivaley, new discoveres and so for. Marmalade Boy the movie, take you back to the start of the anime, and show how yuu fell in love with miki, which was before miki meet yuu, which was not shown in the anime.