This manga is one of my favorites as well as an anime. I've always had the fantasy that this manga portrays me! Seriously. The rocker named Nana, not the other Nana nicknamed Hachiko.
On a serious note, this is a manga about two 20-year-old women who share the same name. Even though they come from completely different backgrounds, they somehow meet and become best friends. The world of Nana is a world exploding with sex, music, fashion, gossip and all-night parties.