Nana

From Viz:
Nana “Hachi” Komatsu hopes that moving to Tokyo will help her make a clean start and leave her capricious love life behind her. Nana Osaki, who arrives in the city at the same time, has plans to score big in the world of rock ‘n’ roll. Although these two young women come from different backgrounds, they quickly become best friends in a whirlwind world of sex, music, fashion, gossip, and all-night parties!

Note: Won the Shogakukan Manga Award for shōjo in 2002.