Ok heres what I think. Punpun cannot leave the city because Sachi needs him. Aiko will realise this and do smth idk what
I have this weird feeling that in the manga, it will just be a join suicide with Aiko and punpun. I keep remembering what Seki's co worker said about just standing their and letting your friends and friends mother die aswell as you..so that you live with no regrets.
Maybe that was extreme foreshadowing idk. But its clear that Aiko and punpun cant live happily in the current state that they are
It truly is hell seeing your one hope in life that you lived for so long to finally see, just bring you down even further