I really didn’t know what I should to think about this manga after few first chapters. It started as typical Japanese horror comic, but genre was changed so many times so finally I can’t rate this manga as horror only.

First of all: story. It starts with sooo typical story line, with “boring school life”, average male main character, of course our student is useless like everyone, no only in normal life, but also when deadly magical girl come to school and start to kill everybody. Then bloody massacre is stared. One by one, every new character after few chapter die in silly way. If always think that horror should make you scared, no this one. Character of story are changing few time between bloody horror and shounen with heroes who are becoming stronger despite the wounds, uh. And the end is just disappointing, and no horror at all.
Rate a art is problem for me. For one side corpses and environmental are very good, but from the other side a bodies of female characters are just… bad. You know, I don’t expect perfect drawing, but when you try to draw semi-realistic (as much as manga style allows do it) be consistent. A bust isn’t two bags with water, and why high school girl have chest more than 50 years old women who give birth 10 children… That was very distracting. No only that, all morphology of characters was cursed, as like a physic, human body can not by tear like that, more than scary it was funny and dump.
One of the main thing that make me angry when I was reading this “horror” manga was characters personality. I know that flat personality is one of characteristics of this type of manga but disproportion between main and episodic role was very unbalanced. When main characters try to fight and survive, people in the background just scream or/and beg for mercy.
Summarizing, for the last 55 chapters (manga have 64) I was thinking only about why it’s still going. My only enjoyment was when somebody was smashed, crushed, cut or blew in some curious way, that’s way I just can’t give this manga good review. However if you no cares about logic or anything literally in manga, this can be good for you.