We were struck at the recent Book Expo America show by the common threads that connected stories of 'hidden' manga consumers in both stores and libraries.  The availability of comfortable reading space and easy access to big manga selections have long attracted readers to big box bookstores such as Borders and Barnes and Noble.  The theory of these retailers is that consumers that come to sample will also buy, but there's definitely a subset of visitors to such stores that read the complete manga volume in the store and don't purchase it.  Now there's at least some evidence that the problem has been recognized and is being addressed; Shojo Beat contributing editor Eric Searlemen told attendees at a BEA panel that a Borders store he frequented, on Union Square in San Francisco, had begun packaging all its manga titles in plastic, regardless of content. 

We also heard that there's at least one store in the U.S. (in New York City) that is renting (Japanese language) manga, a practice that is becoming widespread in Japan and irking publishers with its presumed deleterious impact on sales. 

A similar dynamic also obscures circulation figures in libraries.  Some readers simply visit libraries and read manga there, without checking them out; the relatively short reading time makes that possible.  And we also heard librarians talking about what they perceived as unusually high pass-along rates for manga--one person checks out a manga book, but several may read it while it's out to that single library patron.