You can tell Japan's plummeting birth rate situation is really dire when someone reports a small group of kids in a park as suspicious people, and the cop himself didn't just turn around when noticing it's nothing but a few children. Instead the police officer comes and asks the school kids what they are doing. In other words, children are becoming such endangered species in Japan that the general audience doesn't even recognise them and the law enforcement has no idea how to deal with them.
No wonder they murdered the prime mininister who tried to encourage the Japanese to make more children. Can't have that.