I think it depends how you look at this light novel. But for starters, it's an 18+ light novel focusing on adult material. So, in a way, being porn oriented is expected. Within the 18 chapters that I read, it sums up as a lot of sex related scenes, apocalypse outbreak, food scavenging, base building, zombie clearing, and family searching. And everything but the sex related scenes adds up to maybe 3-4 chapters.

In a sense, it's a really slow novel with a lot of fillers, but in this case, it's porno fillers. Really dunno where the novel will go as the protagonist is still a good guy.

There's a similar light novel with less sex related scenes (not saying none but less). It's called Only I am not attacked in a zombie world, or something. Protagonist can't control zombies but zombies will ignore him. So, he does necrophilia as well. But he's a total selfish ass, who blackmailed a girl to sex. And thinks of using kids as manual labour. Not a good guy protagonist but a lot more plot, so for those who dislike the porno fillers, go try that one.

The concept is really REALLY cool, and so is the outline of the story, but that's about it. It feels like a fanfiction porno of a good web novel. And YES it's that bad. It's almost all sex-scenes. I think that there's like two chapters sofar that hasn't been porn-material, INCLUDING THE PROLOGUE! As I said earlier: Only acceptable as porno, and not even then is it good, since it tries to still have a plot!

Disregard the Porn part

but for me its more like an alien invasion

and this aliens are trying to reproduce using sexual intercourse

The first hint was when they ask if it was really a virus

The second was the growing lust of MC yet he doesn't lust to normal human only to those who has zombified after all he could already rape those 2 girls.