They’re calling for Japan to become a military as well as economic superpower; with an army freed from the constraints imposed by the Allies after World War Two and armed with nuclear weapons. And they want atrocities committed by the army written out of the history taught in the country’s schools.

In other countries they might be dismissed as a lunatic fringe. But their ideas are becoming increasingly influential. Japan’s new Prime Minister Shinzo Abe has declared his intention to adopt some of their ideas as policy, including discussing the idea of nuclear weapons and rewriting the constitution, which threatens to further destabilise the entire region.

The nationalists are stepping up their campaigns - and the use of violence. The team travel with right wingers on their campaigns in the huge sound trucks they use to harangue opponents and travel out to a secret martial arts centre deep in the Japanese countryside where right wingers train with samurai swords. They tell Williams about their willingness to use force to keep Japan on the “correct” path.

The team meet those who have been on the receiving end of this treatment: a newspaper editor whose writers have been attacked, a senior politician whose mother’s house was burnt down by a nationalist in August and a young woman whose politician father was murdered by a knife-wielding right winger.

The victims claim that the right wing’s apparent freedom to organise and carry out attacks is terrifying people into silence – and severely threatening freedom of speech in Japan. Some also claim that right wing groups are just the foot soldiers of nationalist politicians who use them to promote their agenda and scare opponents into silence. Many of the right wing groups are bankrolled and supported by the Yakuza, the Japanese mafia. Unreported World interviews a senior boss who claims that the allegations are true - politicians often pull the strings of right wingers on the streets.

Ordinary Japanese tell Williams that in their view there is no doubt that a ruthless new nationalist line is being pursued by the government and senior politicians. The team meet Japanese teachers rising in protest against new laws ordering students to salute Japan’s wartime flag and sing the wartime national anthem. They meet one of the teachers who have been sacked for teaching students the true history of Japan’s wartime past.

They also talk to a leader of the North Korean community in Japan which has been the target of violent attacks by right wing groups. They claim that the government has barely lifted a finger to protect them.

On the last step of their journey the team gain access to manoeuvres by the Japanese self-defence forces. No-one can tell where this new nationalism will take Japan - and what the implications will be for the world.