WARNING: A number of the comments below this one should be in SPOILER tag, as they spoil the ending for you. This comment does not contain spoilers.
This is a mixture of NHK and Kiseijuu. It's truly an epic read. The manga starts really slow and picks up I around volume 5-6. Towards the end it becomes hard to put down. This is nothing like the movie, which is purely a Zombie flick.
The manga is about the journey of Heido as the world around him collapses due to unknown viral infection that is transmitted through the blood/saliva of the infected. In other words, usual Zombie like infection. We follow the main protagonist, an Otaku; though intelligent in some ways, when it comes to social skills and common sense he seems to be somewhat lacking. As well as being socially inept, shy, emotionally detached, he suffers from episodes of visual delusions. He also has strong desire to abide to the written law rather than the spirit of it, no matter how impractical it is in the current world. We follow him as he and his companion(s) try and survive in this zombie infected world.
Positive aspects:
The best aspects of the Manga are the internal emotions, lack of emotions, social interaction, relationships between humans and recalling of past events (flashbacks). I may have attacked the way the author deals with early reactions of government (below), but the way he portrays Heido, is fantastic. Heido suffers from emotional disconnection, which is truly captured in the last few volumes. He tends to run away from real world and his own emotions when things get to hard. But he tries to change himself and he does succeed sometimes.
Heido has an unhealthy obsession with being a hero as though it is a profession. Outside the DC/Marvel world "heroes" do not exits. People can be heroic and there is plenty of that in the manga. There were so many heroic acts by many (forgotten) individuals.
Other "side" characters also have a childish obsession with "heroes", either wanting to be one or seeing another as one. The biggest contrast is between Korori, who does not see himself as one but has a person whom he idolises as a "hero", and Hedio which wants to be become one. While both men are seen as "heroes" by others; the way they see themselves is not similar and by extension their emotional maturity, and the acceptance of one's fault and personality is also different. This in a black humour sort of way, is shown in the last few volumes. I cannot find the right words for it, but as you read the manga you may understand.
One thing I have to say but you will not understand unless you read it,I am glad Korori
never turned around.
Had he, I believe the manga would have ended differently.
Negative aspects:
Though I said the Manga's Hideo is less stupid in some ways, he is still a total retard. In fact most of the Japanese population seem to be retarded. Even after several days the people still seem to behave in a blissful unaware fashion. And why in God's name do they not notice infected people, with veins all over their face and stuff. They just continue as normal and only react when several people get taken out and the SHTF. The first guy having his face bit does not garner reaction, it has to be a few before people react. Even the police, who one would think would be the most informed and react the fastest are absolutely useless. Slow is an understatement for their inability to respond in a timely fashion. Also no one seem to convey what is going on to others, they just shout in pain and talk about random daily stuff. Why didn't anyone try explain to those around him their ideas of what is going on, instead of vague statements like I was attacked by crazy people. Even after 3 days and city after city falling, the media pretend nothing much is happening. This much worse than being an incompetent government, they are in cahoot with the virus. A totally unrealistic reaction from the government and the SDF.
Another gripe I have is when Hideo's group are stocking up for food, they only get enough for one or two days, when one would think they should get as much as they can. They leave cash if they have any for the stuff they take, and avoided breaking into vending machines because its against the law in zombie apocalypse. On top of that they are afraid of the law catching up with them because they killed infected people in self-defence. It's OK to kill someone who is trying to kill you, that is the case in every nation on earth. If it was just him, I can say it is a quirk, but he is with a group seem to have the same follies. So there are lot of small things like this, that rub me the wrong way.
The story line has a tendency to time jump and we seem to miss highly interesting sections, like what happened in Chapter 54 in the car. Can't say much without spoilers. These parts skipped were heading in a great direction and would have been interesting to see how things went down. It kinda leaves you guessing.
Final note; some people have complained about the ending, I disagree. The ending is masterful. It's bitter, but also very sweet. Heido truly changed, and all shown in just the latter half of the last chapter. It is satisfying.