Manga? Those comic book-things? I don't see why not, though I must admit I have a certain snobbery about them, I'm getting over that now.
I love manga! Comics and manga are writing. A screenplay is eventually meant to be turned into a film with people or animation. How is that any different? I kinda wish we had a section for them, to be honest....
I'm not huge on manga, but only because I've never really given it a huge shot. The little I have read is usually pretty decent. I do find myself picking up a Superman or Batman comic from time to time (It's so hard to keep up with the story-lines if you're not an avid reader), and I consider some of them to be superb. I mean they may not teach anything about prose, but dialogue and story construction are two huge takeaways! Graphic novels like Watchmen, V For Vendetta, and many others have gotten some truly high acclaim, too, so I don't see why not. Maybe we can learn to appreciate the art more even though it relies on the juxtaposition of words and images to create the narrative. As @Wreybies said, screenplays are written to be made into films, so I see nothing degrading about the visual aspect of a good manga, comic, or graphic novel. Like all writing, there is good and bad. This reminds me of a "comic" book I read last year called Understanding Comics, by Scott McCloud. It really put a new spin on how I viewed the dynamics of comics.
