Karin is a romantic comedy-horror manga and anime (that's light on the horror and loaded with comedy) about a young vampire girl, Karin Maaka, and her relationship with a human classmate, Kenta Usui. The strange thing about Karin is that she's not your average vampire – she loves sunlight, has a poor sense of smell, great sense of taste and doesn't suck blood. In fact, she actually produces blood which she either injects into people when she bites them or, more often, the blood comes gushing out as a nosebleed. The series is great if you're into vampire stories, cuteness, romantic comedies or light drama.
The vampires in Karin are a bit different from the average vampire in mythology. Whilst they do suck blood, each vampire has a specific taste in blood, which is actually sucked out of the person when the vampire feeds. For example, Karin's father Henry is attracted to pride, while her mother Carrera is attracted to liars. They also have no fear of crosses (most vampires are atheist anyway), have no problems with running water, and garlic only turns them off because of their heightened sense of smell. A stake through the heart is usually fatal though, as Henry points out, that was be fatal to pretty much anyone.
As you might imagine, a love between a human and vampire is going to have its fair share of hurdles to get over. Thankfully Karin's "mutant vampire" traits do away with some of them but introduce at least very important problem. Karin's taste in blood in unhappiness – something that Kenta has in abundance. This causes Karin to get fairly regular nosebleeds around him. Kenta also learns fairly early on about Karin's secret life as a vampire and the reason for her nosebleeds but not that his unhappiness usually causes them. He even makes an effort to understand her better which goes as far as offering to allow her to bite him whenever she wants.
Whilst the series does concentrate on the blossoming love between Karin and Kenta, it also explores a few other stories. All of Karin's family – her parents and her siblings Ren and Anju all get some air time. Anju, especially has a rather sad story of her adoration for her older sister and how she realises that Karin's differences and desires must one day take her away from the family. Ren is the typical playboy who feeds on the blood of woman suffering from stress. Henry and Carrera don't get much back story but we do learn that they're really typical parents concerned for their children. Henry especially plays the role of the "concerned father of a teenage girl" and often fumes about how close Kenta and Karin are getting.
There's also a few more side characters, such as Karin's best friend Maki Tokitou and Winner Sinclair, a vampire hunter who's (ironically) in love with Karin. These characters are developed a bit as the series goes on and provide fairly crucial roles to the overall story in some parts.
The main plot concentrates on the day-to-day struggles of Karin but later takes on dark tones and becomes a story of the Maaka family being hunted by the Sinclair family, bent on revenge for wrongs done to their ancestors.
I have to say that I really enjoyed this show. I started reading the manga a few months ago and only recently acquired the anime. The anime has fairly good production values (and I like the widescreen aspect ratio) and the voice acting is very well done – it'll be interesting to see what the American version is like. In terms of things to fault I'm struggling to find something. I love cute romantic comedies and vampires so I was pretty much destined to love Karin. As usual though, I dislike the typical Japanese approach to romance where we get through 24 episodes and the main couple don't even kiss. At least in this there's a dramatic biting scene which kind of makes up for it. I also had a few niggles with fan service (such as ridiculously jiggling breasts) during tense, dramatic moments.
The anime ends in a nice place but I'm glad that the manga is still ongoing as I really like reading and watching these characters and want to see more!
Overall, a great series and one that I heartily recommend if you're into anime and manga.
UPDATE: You can read the review of Karin DVD 1 at Anime News Network. Sounds like the English dub leaves something to be desired.