I'm not sure whether the "manga" here refers to comics (books) in general, or Japanese-styled ones in particular.
If the former then it's best to translate it into "comic (book)" instead of leaving it as "manga", but for now, I'm just going to stick with "manga" in the TL, but things might change depending on what I can glean from future chapters. (And looking up and comparing Western and Japanese comic book practices.)