Aw hells ya, Nana
I jumped in and skipped the first dozen episodes after only watching the first one. It's pretty easy to see what's going on from there, then it just snowballs without stopping until the end of the series.
EDIT: This is probably old, but new to me:
Nana voice cast, Ocean Studios
Kelly Sheridan (Nana Komatsu)
Rebecca Shoichet (Nana Osaki)
David A. Kaye (Shin)
Matthew Erickson (Nobu)
Brian Drummond (Yasu)
And others labeled in the credits