We have plenty of films depicting WW2, but not as much about when it ended. For the surrendering countries, the end of the war didn't mean peace. Despite the war being over, returning soldiers were still taken as prisoners of war by Soviets, shipped to Siberia as mentioned in the film; families were separated, taken to interment camps, and the conditions killed many.
This movie encapsulates and beautifully illustrates the Japanese experience of the 'end' of WW2. Each character represents a different attitude taken at the time towards duty and country, giving each attitude its justice without bias.
It's amazing to see the history of my German great grandparents reflected in this film, despite it being about Japan; this history is often entirely neglected since they were the bad guys, but through stories like these, we experience these hardships and sufferings overlooked by the world. The film represents both the Japanese and the Soviets as humans, likewise important despite the harm the USSR did to Japan.
The impact is great yet simple, a very enjoyable film, not too heavy yet plucks a few heartstrings still and leaves an impression. The animations is lovely and drives home the themes of the movie.