Among other things, this Fall season features a pair of intriguing visual novel adaptations, Grisaia no Kajitsu and Daitoshokan no Hitsujikai. The two are somewhat dissimilar titles, but have quite a bit in common on paper; both series are quite popular (the franchises took the #4 and #1 spots in they getchu 2013 rankings, respectively), and have already won their share of hardware (Grisaia at the 2011 moe game awards, Daitoshokan in the 2013 getchu user awards). Perhaps even more interestingly, both series ostensibly swapped their original PC voice casts for new ones in advance of the anime. I say ostensibly because they didn’t actually swap their casts out at all; the same people who have been doing the voices for the franchise from the beginning will be doing the voices for the anime adaptations. This is also the case for the third non-Fate VN adaptation of the season, Ushinawareta Mirai wo Motomete. In practice, the reasons for these name swaps are fairly straightforward – voice actresses tend to avoid using their real names when voicing works that contain adult content.
Looking into recent history, I found a number of such cases where the original VN cast dropped pseudonyms to work on the anime version, with such titles making up a plurality of non-sequel VN adaptations over the BD era. That same history suggests that some combination of factors contributes to higher odds against them making it big as anime.
Sales tracking site someanithing lists a total of 41 shows made from 2009-2013 that were based on visual novel source material. Of those, 10 are sequels of a previous-season show, and 4 are hard to classify for various reasons,* leaving a final sample of 27 shows we can parse based on whether or not they tweaked their voice cast info. 12 kept everything the same, 13 swapped out pseudonyms for (presumably) real names, and, in the remaining 2 cases (Princess Lover and Phantom), the voice cast actually changed from game to anime.
While this sample isn’t big enough to draw concrete conclusions about either subset, it is suggestive that adaptations of games with adult content have a harder time breaking out to become big or even moderate hits. The 13-series pseudonym-adaptation subsample contains a total of only 3 anime to average above 3000 disks per volume, and only one of those, Little Busters, broke the 10k mark. That’s a stark contrast with the more successful same-names subsample, where 7 of the 12 series broke 3k and three (Hakuouki, Steins Gate, and Uta no Prince-sama) handily cleared the 10k hurdle.
There’s a number of reasons why the latter sample could be outperforming the former. One obvious answer is that the presence of adult content generally deters mainstream audiences, and shrinks the potential incoming fanbase even if the makers also release all-ages PSP versions in the runup to the anime (e.g. Mashiro-iro Symphony). Truly A-list voice actors may also be less likely to do adult content, potentially due to brand concerns or even simply having more financial security, which leaves the makers forced to either stick with the cast they’ve got or take a big gamble by swapping up the cast. While exactly how important voice actors are to any given show can be tough to quantify, it’s at least worth noting that the vocal cast was a major strong point for both Steins Gate and UtaPri.
Again, it’s probably not good to over-analyze a relatively small sample. You can go back to the format war years when BD wasn’t as prominent and find plenty of success stories adapted from non-Key adult VNs; the second Da Capo series, ef, OtoBoku, etc. I think any of the three fresh VN adaptations this season could pull off respectable sales numbers, just that they would be beating the odds set by the recent past in doing so. I personally will continue to believe in Daitoshokan no Hitsujikai until forced at gunpoint or by awful on-field performance to think otherwise.**
*Total Eclipse’s game came out well after the anime, Canaan was very loosely based on a game’s bonus scenario, and White Album 1/Umineko no Naku Koro Ni were both originally no-voice games.
**I put all my chips behind Team Nico about a month ago, and I ain’t changing horses in midstream on that one without a damn good reason.