As other have said...
Overall a good series. Tons of cliches (suddenly beautiful girl hanging around guy acting unconsciously suggestively and all the other guys act ridiculously, the guy is the misunderstood tough guy type, some other cute girl randomly decides to fall in love with the main character...).
But I thought they were really doing a good job with the romance in the second half of the last volume. There was one panel where Lilim is questioning her sudden feeling that was cliched, but otherwise it was subtle and excellently done. And the series-end "crisis" (yeah it was the usual deal, near the end there's a relationship crisis and they manage to overcome it but still haven't clearly stated feelings) was really excellent, too.
But the last couple of developments (don't want to be too specific--trying to "open it", and then the aftermath of that) were really rushed. In general terms--for this type of series wrap-up, there's a "crisis stage" where some crisis occurs, a "determination stage" where the characters work to overcome their inner conflicts and finally act to overcome the crisis, and an "aftermath stage" where the story showcases a few choice interactions between characters to show you how are between the characters after undergoing the crisis. The crisis stage was really good, but the determination stage was really stunted, and the actual cathartic moment which concludes the determination stage was artistically done but the meaning of it wasn't very clearly conveyed, to me at least. Then, the aftermath stage was like, 1 page, and totally didn't acknowledge the massive amounts of character development that had happened. Plus they never really referenced the meaning of the "earlier Lilim" in the one flashback.
So yeah I enjoyed most of this series, it had a lot of potential and used quite a bit of that. If the mangaka had drawn just a few more chapters they could have really developed things and drawn from the story potential that had been hinted it, without the story getting stale. (I'd ask for a 12-volume run or something but even with 2 volumes the mangaka had already been wasting time with Miu-oriented plots and an admittedly adorable mascot character, so just a few more chapters added to the concluding arc would've been great.) Or a sequel to this series which starts off by making clear that the relationship between Takaya and Lilim didn't completely devolve by the end of the first series, where at some point Miu recognizes Lilim is her good friend (kinda like the succubus in Rosario+Vampire getting to be friends with the vampire lead character) and is a supportive/cool character, and that annoying pseudo-friend of Takaya's gets a girlfriend to shut him up and keep him in line, and together Lilim and Takaya re-explore and reconcile Lilim's past and memories... Ahh, that would be good stuff, too bad it's never going to happen.
By the way, I only found this series by chance, seems odd I missed it earlier but then I realized there was no supernatural tag added to it. Though I guess the supernatural isn't that explicitly prominent in it, it's just what the supernatural brings to character development (like humanity & inhumanity, for one) that is very important.