The Kuril Islands Dispute is a dispute between Japan and Russia over the sovereignty of the Southern Kuril Islands. These islands were occupied by Soviet forces during Operation August Storm at the end of World War II, which in the end are claimed by Japan which refers to them as Northern Territories, Southern Chishima, being part of Nemuro Subprefecture of Hokkaido Prefecture.
Not wanting to go on too long, there was a San Francisco Peace Treaty which stated that Japan should give up all claims to the Kuril Islands. There was a big fight between Japan and Russia over these islands.
Japanese government produced an isekai anime.
In the end, through a resolution of the European Parliament, Russia ended up returning the Southern Kuril Islands to Japan, and to promote the territorial claim to the Southern Kuril Islands, the Japanese government produced a short isekai anime that tells the story of story of a girl who is run over and wakes up in 1945, where she experiences the Soviet invasion of the islands:
As you can see, it’s a very cute anime, very interesting to watch and that helps us to have an idea of the terror that the Soviet invasion was.