Japan is one of the most media-saturated societies in the world. The circulations of its big five national newspapers dwarf those of any major American newspaper. Its public service broadcasting agency, NHK, is second only to the BBC in size. And it has a full range of commercial television stations, high-brow and low-brow magazines, and a large anti-mainstream media and mini-media.

Japanese elites rate the mass media as the most influential group in Japanese society. But what role do they play in political life? Whose interests do the media serve? Are the media mainly servants of...