Waaaaaay back in February of this year, I caught wind of the announcement of a Kurenai OAD, to be bundled with a future edition of the manga. I was a very big fan of the anime series and I consider it one of the highlights of 2008. I was under the impression, based on forum discussions at the time of its broadcast, that many other people thought highly of the series as well. I was surprised to find, however, that following the announcement of the OAD and the broadcast of its preview, many people (though not a huge majority, by any means) seemed to laud the new production's closer adherence to the manga's character designs, and to voice their disdain of the TV series because of how different its tone was from that of the manga.
Both the manga and the anime are adapted from a series of light novels, and while I know next to nothing about the story and tone of of the novels, it doesn't surprise me to hear that the two subsequent adaptations are so different from each-other. For example, the anime version of Le Chevalier d'Eon tends to focus more on the historical backdrop of its tale and how the supernatural elements are woven into the story. The manga adaptation, however, brings the supernatural and cross-dressing elements to the forefront. The anime comes across as more mature and serious, while the manga is not much more than very pretty fetish-fuel. The point is that a set of basic ideas and characters can inspire other creators to go off in multiple directions and it's not that unusual to learn that, in the case of the various Kurenai adaptations, there seem to be plenty of discrepancies between the two secondary works.
Out of curiosity, I sought out chapters of the Kurenai manga for comparison, and was honestly pretty disappointed in what I found, mainly due to a major difference in tone from the TV series. Part of the appeal of the TV anime was how it was able to maturely handle some very serious subject matter, and how it also became a commentary on the role of traditionalism in Japanese society and the ways in which Japan might solve some ethical dilemmas that arise when tradition tramples on human rights and the dignity of others in modern society. None of the characters felt typical and despite the fact that the majority of the characters are female and that the show is centered around a male protagonist, not once did I get the impression that a harem was developing. There was a good amount of humor in the early part of the TV series but it never seemed as if it was going to devolve into some corny slapstick comedy. The series even lamp-shaded any concerns the audience might have about there being any lolicon fuel early on with a particularly amusing misunderstanding between the main character and a friend at school, and it was obvious that that sort of content wasn't going to have a home in the series.
The manga, on the other hand, seems to fall into every shounen genre trap laid out for it (at least within the first 8 chapters, which is where I really began to lose interest and decided to stop wasting my time). The story is oversimplified and formulaic, and the characters are all one-note caricatures based on a host of obnoxious types, with many of the females harboring obnoxiously-dimwitted crushes on Shinkurou. Tamaki, who in the TV series tried to give off the impression that she was worldly and experienced with relationships but who was really just as vulnerable as anyone else, comes across as a sex-crazed goofball intent on getting Shinkurou into sexually-uncomfortable situations. Yuuno is a jealous bitch who begins to rage every time she sees Shinkurou and Murasaki out together. Ginko is a Tsundere (my personal anime kryptonite). There are fanservicey jokes that make the aforementioned characters look like fools. The character designs, which seem to be one of the major reasons manga fans disliked the TV anime, are cutesy and only serve to make it look more like every other manga. It's honestly like a lot of other really mediocre shounen series.
So to me, saying that the OAD will be more like the manga is a good enough reason for me to stay away from it at all costs and hold onto my good memories of the TV series (or heck, even give it a good re-watch). However, I'm holding out hope that it won't dip to the manga's depths and will retain at least a little bit of the things that made the show worth going out of one's way to watch. At the very least, the OAD may lead some people to seek out the TV series and enjoy it, which is definitely a good thing.