Securing government after a Japanese naval defeat

Would an early defeat leave Japan under military rulers rather than a stable democracy?

It could, which would force the victors to consider measures for securing the Japanese government after the fighting ended.

A defeated fleet does not by itself guarantee a stable democratic settlement. The Army could claim that it had lost no battle while the Navy bore the visible defeat and sought to restore its standing as the government negotiated an end. Returning military forces and a government facing humiliation could produce a series of military rulers. If that danger appeared likely, the victors would have to decide how to secure Japan's government rather than ending policy at the armistice. The scenario remains open because it has not specified an occupation or constitutional programme. Postwar political control is therefore part of war termination rather than a problem that naval victory automatically solves.