For years, they have been a noisy and constant presence outside the gates of Japan’s national broadcaster, NHK: rightwing fringe groups, complaining through megaphones about supposed liberal bias in the public network’s programming.

War documentaries, news coverage of China, even South Korean soap operas – it seems there is always something on NHK’s numerous television and radio channels that infuriates self-appointed guardians of Japanese patriotism.

Now, the protesters have an ally in the most important office in the country. Shinzo Abe, prime minister, has sparked an acrimonious debate about the role of NHK by engineering a change in its senior management, part of what some observers see as an effort by the conservative leader to reshape Japan’s cultural and educational institutions.