A Japanese comic book read by sadistic weebs who can't be asked to commit to reading a proper book. If you tell a weeb that manga isn't a proper comic, run.
"manga isn't a type of book, they're just dumb comics for kids."
mangas are books that are usually planed out before a anime release. most people who reads manga might or might not accidently spoil everything that you might not had gotten up to yet. watch out for manga and light novel readers if you are a anime fan.