Junpei and Kanta were very young during the war but even they can see how things have started to change since it ended. There's a new tension in the air and when the Russian's occupy their small island near Hokkaido everything becomes worse again. No longer free in their own homes, the two brothers adapt and stay cheerful but there's a limit to how much you can do when the Russian's have other planes for the island.
This story isn't set during WWII but I would still argue that it's a war story just the same, even after a war officially ends the effects are still felt for years even in the best cases. For Junpei and Kanta there's a much more visible reminder after the Russian occupation, it's almost heavy handed and a lot of the movie is heavy handed to be honest. I'm not sure if the story was intended for kids and that's part of why it has "the emotional subtlety of a sledgehammer" or if it was just in an effort to re-create the mindset of a child since that is the point of view of the main character. Either way, while I was able to understand on an intellectual level "oh we're doing this to show that, and now that happened to connect to this earlier event" it just didn't connect with me emotionally at all. That's an especially tricky balance for war stories in my opinion, to really stand out you need to show the audience war in a way that they've never thought of before and this story didn't quite do it for me. In a way I was both too removed and have heard so many horrendous things happening to populations of occupied lands that watching the later part of the movie felt like watching the news: I was too numb to try and connect after seeing everything that had come before.
I did go into this movie expecting to be a sad one since it is based off of a real life inhabitant from Shikotan (island), but I'm left wondering how many of these events were real. The budding romance between Junpei and Tanya left me suspicious but most of my disbelief came later in the film where it pairs up these horrors of war with elements of a children's adventure film. The brothers go on a seemingly impossible journey and the fact that they didn't die several times over just didn't quite mesh with the uncaring world they were living in . My problem actually wasn't with the fantasy sequences earlier in the film, I wasn't fond of them but thought that they had a purpose and could understand the reasoning for them, but I also felt like the end of the story was being overtly emotionally manipulative and I don't appreciate that! The one "war story" that I've read in recent years that I really connected with (Nella Last's War) really hit me because there were so many little moments that made you go "oh, so that's what this means", not Big Important Events.
So this wasn't the movie for me, I don't want to write it off as a bad movie however and do think that more people should see it in any case. Sadly, it's not online anywhere I know of and it appears GKIDS still hasn't put it out on DVD yet but that is the plan so hopefully both of those happen soon!