Well first of all, Japan can always adopt American born children I think we have a large population of new born here in the USA, if not us then in other countries like somewhere in Asia and Africa.
With all joke aside, according to CNN news this morning, https://www.cnn.com/2018/12/23/health/japan-birthrate-record-low-intl/index.html “Japan suffers biggest natural population decline ever in 2018” and they’re predicting that by 2065 their population will reduce to half if nothing is being done about. To me it’s just surprising for an advance country such as Japan population is decreasing, however I think their government will do something about it, to stabilized the population. If recalled back correctly, the death from gun violence in Japan is like 1 annually, but the death from suicide is a lot greater, most death caused by suicide due to career failure including business.