I rarely ever write reviews anymore due to having no free time, and definitely don't have time to write a full-fledged writeup of pros and cons - but Pupa was so disturbing that I feel compelled to at least write a warning to others.
I was first interested in Pupa when seeing the upcoming Winter anime list, as there's an anime adaptation airing soon. Horror? Check. Disturbing? Check. Anyone who knows me, knows I love me a good horror title, and try my best to read as many manga related to the genre as possible. It takes a lot, and I mean a lot, for me to be grossed out and disturbed by something.
Look, the story isn't bad - it's kind of interesting and at least it's somewhat unique. A girl gets randomly infected by a virus, there's a nefarious researcher who knows more than she lets on who offers to 'help', etc.
But really, Pupa pushes the line for gore and disturbing. Unless you like watching people slowly get eaten alive over and over, or someone getting vivisected while conscious/alive, I'd suggest looking the other way on this one. Hands down.
tl;dr: this is too disturbing even for me. :|