Japan's record of more than 107,000 centenarians, sustained across 56 unbroken years of increase, arrives not as pure triumph but as a mirror held up to a civilization navigating the consequences of its own success. A society that has mastered the art of living long now confronts the quieter crisis of living few — with births numbering fewer than the very old, and a workforce too small to carry the weight of those it must sustain. What Japan has built in longevity, it is losing in continuity, and the choices it makes in the years ahead will serve as a template for much of the aging world.