A metafiction comic in this case is a comic inside another comic or when a fictional character comments about other fictional characters but without need to recognize its own fictional reality. The reader can read also the metafictional story (the full story or only segments).

Sometimes, the metafictional story can break the fictional fourth wall, in-universe, but not always and not necessarily the readers' fourth wall.

A good example of this concept is Watchmen where a boy reads a comic about pirates, (Tales of the Black Freighter) which it's a different story itself yet had certain relevance to the main plot.