Korobooshi Kojiro
Funnnngaaaaa
You have a really ignorant preconceived notion of the growing popularity of manga. It really hasn't reached mainstream U.S. yet, per se, but consider that types like Naruto, Fruits Basket, Death Note, Bleach, etc. are cracking into the top fifty in the freakin' best-selling book list, you'd have to be an utter moron to deny its steadily increasing popularity.
I love the irony here.
I take it you've never had the pleasure of meeting Justin-sama?
Anyway, I have too say if Captain Underpants is considered a book (and even makes the Banned Book List), then I think Manga is a book.