Marmalade Boy

From Tokyopop:

All Miki Koishikawa wanted was an ordinary family and that’s exactly what she had until her parents decided to move in with another couple and turned Miki’s world upside down. Now she lives in a house with four parents and her totally cute stepbrother Yuu. It’s bad enough being brought into her parents’ strange soap opera, but Miki will star in a soap of her own as she deals with friends having affairs, trying to survive in school and ending up torn between her long-time crush, Ginta, and her new stepbrother!

Title: Marmalade Boy
Creator: Yoshizumi Wataru
Status: Complete
Genre: Comedy, Shoujo, Drama, Romance, School Life, Slice of Life