New Delhi, Feb. 13 -- THE LIBERAL DEMOCRATIC PARTY (LDP) has dominated Japanese politics since its founding in 1955, ruling with only two brief interruptions. Never has it won as decisively as it did in a snap election on February 8th, when it took almost 70% of the seats in parliament's powerful lower house. Takaichi Sanae, the triumphant prime minister, now has a historic chance to transform her country. She must not squander it.

To live up to the expectations that her electoral gamble and huge victory have created, Ms Takaichi needs to think bigger and broader. She cannot treat her time in office as routine, focused on short-term relief to ease the pain of today; she must take Japan's long-term demographic and economic challenges head...