Manga to me is just a simplifyed way of drawing humans. Alot of manga's are Idealistic and shows us what we want. Art is to express ones ideas or dreams in anyway, drawing is one of these ways. To make Manga you have to draw Manga, and all Manga lines come from an idea that is then processed onto paper. So to me, Manga is art, no matter what genere it is (big busts and all) it is art because it came from an idea and then was expressed.