There are volumes which haven't even been published yet on some Earths, ones non-existent on others, and there's complete collections of hundreds of volumes. Shoujo and shounen are prevalent, but any genre, subject, romantic pairing, or level of smuttiness can be found.

Though, the smutty manga volumes are sealed in plastic and if you try to remove it, you'll find Lexi behind you, not even bothering to be subtle in her glare which says clearly "put that down."