‘Marmalade Boy’
Miki’s parents come home from their vacation to announce that they are getting a divorce. But what is more shocking is that they have switched partners with another couple! And to top things off, this other couple has a handsome son, Yuu, who Miki begins to develop feelings for. To make things more disturbing, everyone moves into one house. What will everyone think about Miki’s family lifestyle?
Descriptions taken from AniDB.net