Population of Japan is projected to be 50 million (25 million of those in productive age) in 2120, that seems like enough to defend the relatively small island

Population of Japan is projected to be 50 million (25 million of those in productive age) in 2120, that seems like enough to defend the relatively small island nation. Source: https://www.jcer.or.jp/english/new-population-projection-how-does-it-differ-from-the-old-one https://www.jcer.or.jp/english/new-population-projection-how... > It could be roving groups of displacees who took up piracy and invasion. See the Sea Peoples at the collapse of the Bronze Age. They'd have no chance against an organized professional military, esp. in foreign environment, no chance to blend into the local population etc.