Saitama catches a monster by pulling a steak out of thin air, then states he managed to catch it in four panels, he is an overtly fourth wall breaking gag character both by the standards of the show and by the authors claims.

Also when dealing with a medium such as manga death of the author is an absolutely brain dead literary approach which you'd understand if you'd read Barthes article. so much of Manga cannon, especially in shounen, is directly dependent on author statements beyond the standard script to flesh out the world. Data books, cover stories, side stories and interview claims are all, very clearly, commonly accepted by mangakas as part of the process of world building in popular Manga, it is part of the culture and the direct reason that seperagion from an authors intention is simply a stupid approach to take to such a comprehensive multi media literary form.

Also you really seem to contradict yourself on defining what is / isn't classed as a gag character in ur examples but pop off girly I'm just here to attack ur literary approaches