I'm always amazed at how fucked up Punpun seems to become after being raped at an early age by what's her face. Because i think about that moment, and I think about all the times Punpun has consequently thought of rape. It's always as a sort of 'take' because he is miserable and lonely he has some sort of justification for it in his head. He never does it, but he does think about it. Of course this is a direct result of someone using Punpun at an early age because they were lonely and miserable. This is also around the time I think the bird metaphor starts to change, as Punpun's visual style also starts to differ up. To me the bird is a changing and evolving metaphor, starting out as childlike innocence and warping from that as we see Punpun's character change while retaining that bird like image. Punpun begins with a very innocent outlook of the world and his own terrible situation, and as the story progresses the idea of his own 'innocence' becomes tougher to justify. In his teens, as he thinks about raping that girl on the date(because the only real interaction he's had with a girl sexually has been rape) the image of the bird becomes awkward in the reader's head. The bird image is supposed to make you a little uncomfortable after this point, and the consequent changes like wise. When it suddenly changes to a cube, and the little to no emotions or movements Punpun displays become a worrying as both others and the reader don't know what is happening or what he is thinking. As it becomes black and sinister, you know he's gone off the deepened, yet it still retains that birdshape; that now warped sense of 'innocence' as we see how the cute bird has grown up. At the end when we last see him technically presented as a stranger, only recognized really by his bird like form. The last moment is in such an interesting contrast, because he is seen by a childhood friend, someone at that initial point of the bird, yet they cannot recognize him, as a now adult Punpun is surrounded by new friends; creating a final contrast of where we started and where we ended, and how much this one child has changed into his adult hood.