For anyone who wants to get into drawing Manga, I highly recommend Mark Crilley as the way to start.  Mark has his own Manga publications, as well as a comprehensive how-to book just recently published.

His Manga series Miki Falls is being turned into a movie by Paramount Pictures.  Other series to watch are Brody's Ghost and Akiko.  He is an amazing artist, and his tutorials on YouTube are fantastic as well.  Check him out.