This is a children manga that criticizes imperial Japan's propaganda and inhumane treatment of both civilians and POV during the war in a forthright manner. This topic comes up a lot in Fujiko F. Fujio's series, but here it feels very personal.
I always feel Mami's dad is a stand-in for the author. He's very involved and has more lines than the typical parental figure has in manga. In real life, Hiroshi Fujimoto also grew up in post war Japan and had a daughter. And of course he was an artist like Mami's dad, though in a different medium.
