This story about an 11-year old boy growing into adulthood is not what you would expect out of a shounen, or a seinen for that matter. Its stance against what religion, happiness, and adults teach us is nihilistic in the darkest meaning of "nothing matters". However, I gave this 10 stars, and here's why. I'm not anything special, and the world won't ever know my identity for another generation or two. This book made me think about how much my interactions affect people, how important it is to be honest, and the impact that communication can have for a person.
This manga is very lonely, and triggered a depressive state to finish this manga to completion. But, after thinking about what the author intended, I believe that the author was showing us what would happen if we took the wrong path every time. We already know from countless mangas what will happen if we continuously make the right choice, but this one has a deeper meaning to it all. I think we all relate very closely with Punpun, and the "masturbatory" monologues that people seem to think happen in this manga are well thought out.
Every character knows what they must do, but don't do it because it doesn't seem reasonable enough. This book does not speak to the mind, but the heart, and shows us that our decisions are more than just reasonable interactions, but emotional ones, and if we don't communicate those emotions with others, we will end up making the wrong decision.
I think that this author really wanted to shape a character that felt real, and there are moments that the manga speaks directly to the reader and shows the author's intentions and frustrations, like when Sachi is arguing with the publisher.
Therefore, this is not a manga for the people who want an easy read. This is for someone in a rut, someone who has forgotten their place in life, like Punpun, and need to see what their life can turn out like if they push people away. So hold on tight to your loved ones, because this one will make you want someone around you for the rest of your life.