Pinpointing the true source of power in Japan is a notoriously slippery task. In a society where decisions tend to emerge through a drawn-out process of consensus, even prime ministers are sometimes little more than figureheads, articulating policies engineered by anonymous others deep in the bowels of the body politic.

One man, however, who has enjoyed undisputed influence is Tsuneo Watanabe, now 80, chairman and editor-in-chief of the Yomiuri newspaper, which with a circulation of 10m is the world’s largest daily. Mr Watanabe, who took charge of the Yomiuri empire in 1991 after starting as a political reporter, has long had the ear of prime ministers, business leaders and elite bureaucrats, including other “shadow shoguns” who have helped shape Japan.