tl;dr: A short and sweet romance in a dark setting that's a bit rushed towards the end and kind of narrow.

This manga is pretty short. It's four volumes but it's the type that you sit down reading and before you realize it you've already reached the ending. There are only a few characters, and the story is primarily centered around the relationship between the protagonist and the main heroine and the circumstances surrounding both of them. It is ultimately simply the story of the hero saving the heroine, but I think it does a really good job with how it goes about this. It does a good job of slowly revealing what the situation is exactly, leaving things quite mysterious and not revealing everything until the climax, and does a good job of using that to have the relationship between the protagonist and heroine develop in an interesting manner.

The protagonist is a very interesting character, in that for most of the manga they seem to be the type of protagonist that's pretty weak willed and just goes with the flow, but in the end show that they actually have a pretty strong-willed personality that makes them likable and easy to get invested in. The heroine doesn't have that much to her in that she's mainly just a really kind girl that was in an awful situation, but the horror aspect of the manga is used well to really convey how awful of a situation it is, and thus though it is based on pity that is enough to make the reader heavily invested in her, which is fine for the type of manga it is. The story manages to hit a lot of good emotional notes, and as a result of the strength of the two main characters the plot itself is also really easy to get invested in, and thus these emotional moments manage to have a lot of impact.

Still, it felt like the manga was too short which manifested in two issues. The first is that the ending felt quite abrupt and rushed. It's a really solid ending in and of itself, and the last couple of pages manage to capture an incredible amount subtly, but I think I would have really enjoyed it spending more time on it and fleshing things out more explicitly. The other issue, though this is one that's more of a double-edged sword than just an issue, is that the story managed to capture so little. There is some really strong world building and the manga also does a really good job of establishing the dark tone and atmosphere surrounding that. It shows a lot of things slightly and alludes to quite a bit more, but in the end doesn't really flesh out anything other than what's immediately relevant to the story of the two main characters. Thus, it feels like there's much more story that could be told for this world that simply wasn't. The benefit of this is that the plot of the manga got to focus solely on the two main characters and managed to develop that incredibly well with good pacing. But at the same time, it does kind of feel like we're not getting the whole picture.

The art was pretty good in that it wasn't overtly good in quality or style, but did a decent job of being nice looking when it needed to and an even better job of being horrific when it needed to.