They are catching up, and the art seems better to me with each chapter!
I like your opinion on what the old man represents, truly with the 5th chapter it seems you are correct, he tells it himself that he only wants to listen to them play and not care that much, he is beyond everything now, that is why really young children and really old people mix together well. Old people are not the adults that children will become since they are pass that and children are not the adult the old man once was.
And chapter 5 was Haruo centered! Ah now it seems I do not look at his character the way I did, the first chapter that centered on him was about his bad sides, yet this one was balanced, Makio is a really great parent figure to them, the other caretakers are nor as good with children as he is, he just gives out a positive atmosphere.