Ill have to disagree with most of the comments here.
First, calling the mc retarded? come on its a fucking kid, going through this kind of event. His decisions and psychology are not only completely justified, but believable. Second, 'badly written harem story', incorrect as well. Once again, the development makes sense for teenagers going through something like this. They cling to whatever they can, and want to experience whatever they can, since they could die at any moment. Even for adults it would work like this. If anything, this makes more sense than your run of the mill highschooler with 8 girls panting around him for no apparent reason while being unable to act and willingly even get a kiss from one; which makes up for what, 70% of the harem genre? just go read to love ru, what are you doing here.
And Third, of course there are inconsistencies and absurdity every now and then. Its a manga. Overall, i have to admit i got here for the fanservice not expecting much, but even being a zombie genre enthusiast, the infection parameters and plot development surprised me. Good art, junji ito vibes in a couple of pages.