If you liked the Vexille: 2077 Isolation of Japan anime, the Anime-Planet community thinks you'd like:
Calamity strikes the country of Japan as a series of brutal earthquakes literally tear the island in two. Put in an impossible predicament, the Japanese government agrees to hand control of the country over to the United States and China in exchange for aid. Tensions flare, both at home and abroad in Taiwan, where 80,000 survivors have ended up. With conflicts brewing between the Taiwanese and Japanese and with a violent gang out to cause trouble for their own ends, can anyone broker peace without bloodshed?
Vexille and Taiyou no Mokushiroku are stylistically poles apart, but thematically very similar. Both deal with ordinary people who must unite and rally in difficult circumstances in order to overcome a great power. If you likes this type of struggle in one of the films, then the other might be worth checking out too.