Itogami Island is an artificial island not far from Tokyo, one of the many "Demon Districts" that was home to demons and other mythical creatures. They live along side humans and were protected as endangered species while under observation for research. Kojou Akatsuki had discovered himself one day as a vampire with no memories of his past as a human. Not only that, he wasn't the average vampire either. He had become the "Fourth Progenitor", a powerful vampire that who can take out an entire human army if he desired. However, he has no such thoughts and continues living as a normal senior high student as best as he can while keeping it all a secret. One day Yukina Himeragi is sent by the Lion Organisation in Japan to observe him and was to eliminate him if he was considered a threat. Meanwhile, not all is at peace and Kujo soon finds himself relunctantly honing his skills to protect himself and the island as he is caught up in various incidents.
Show's based on a light novel series and has an interesting world setting. It's not the first time a Japanese title tried to fuse technology and magic together though. Despite the protagonist Kojou being a vampire, the main plot is more about how humans and demons try to live together in harmony but obviously some aren't happy with the way things are. Kojou having just gained the power of a vampire happens to experience both sides of the world and ends up wanting to maintain the peace. His genuinely nice character and heroism ends up winning the hearts of all the girls he comes up across.
Of course, this also becomes an excuse for ample fan service as there is plenty of nudity and your usual "accidental" sensual situations like groping. The female cast willingly tries to arouse Kojou so that he would take their blood during "dire" situations so that he can awaken and take command of a new power. Obviously the show is aimed at the male audience but at the same time, there's just enough happening to stop the show from turning into a complete mindless fan service show. And believe it or not, there's actually romance.
Other than that, background art's good and fight scenes are short but well animated and intense. There's a bit of gore but not too many. The OST is good too but the theme songs are so-so. I first heard Altima's "Fight 4 Real" on Animelo Summer, a gig for Anime songs and it just doesn't fit the S1 OP2.
Characters are cute - you've got Yukina who's easily flustered and, Natsuki a loli AKA "Witch of The Void", a firm teacher fond of gothic fashion. It's fun watching your usual Anime personalities bicker and, your nice guy completely oblivious to all the girls falling for and fighting over him despite all their initiative. The lines "This is my fight!" followed by "No, Senpai. It's our fight!" becomes pretty stale.
The plot barely moves in season 1 and feels like Kojou is fighting against lots of random terrorists at first although, maybe it was just building up the relationships between the characters and revealing more of the world setting. It isn't until the last few episodes of the show, does the story go back to Kojou and reveal more about his powers and forgotten memories. The OVA "Valkyria no Oukoku-hen [Kingdom of Valkyria]" is more fan service focused than the first season with Kojou actually making the moves on the girls but, it does pick up the previous events and continues to develop the world setting. Some hints of marriage too although whether the future series will stick to those pairings we'll have to see.
Second season OVA continues to build on previous events too but finally gives the main plot a big push. It's a wonder (and a ridiculous one at that) that Kojou and co manage to keep everything a secret from Asagi for so long, lol.
Season 3 is abundant with nudity and lingerie scenes true to its fan service nature, with nothing to hold it back as it was a disc release only. While it also sheds some more light on the main plot it doesn't do it very well with a lot of silly scenarios that aren't quite believable even with its equally silly world setting. The direction's quite messy too at points where they divulge too much and you need untangle the mess like there's a sudden rush but it wraps up the story quite well. You can see it's low budget too with characters looking out of proportion sometimes, little detail in scenes and repeated animations. Despite all that it has a cute ending and there's also bonus scenes afterwards so don't miss it.
Natsuki's probably the best character in this being the most mature despite her little appearance.
One for the guys. It's a harem show after all but it's not the kind that's just fan service for turning your mind to mush.