On the tenth floor of a typical Tokyo office block, ranks of uniformed men with Japanese flags and militaristic insignia are holding a meeting.
Reciting a 19th-century Imperial Japanese creed, they call on citizens to courageously sacrifice themselves for the nation and to guard the honour of the Imperial Throne.
They are members of Taiko-Sha, one of Japan's growing number of shadowy right-wing groups. And it is groups like these who are at the forefront of a concerted push to get Japan to move away from its post-war pacifism.
Japan's police are calling it right-wing terrorism and say such groups are on the rise. Under the banner of "direct physical action" the Taiko-Sha are accused of carrying out fire-bombings, beatings, stabbings, shootings, and even their own ritual suicides, to make a political point.
"Using violence is a personal decision," says one middle-ranking Taiko-Sha member, who asked not to be named. "But if the interests of the Japanese nation requires us to use that violence then it is justified."
For the past 60 years, successive Japanese governments have accepted the pacifist constitution imposed after the Second World War, while right-wing nationalist groups have been ignored as fringe extremists.
But a resurgent nationalism among some mainstream politicians and North Korea's recent nuclear testing have meant right-wing groups are now being listened to at the highest levels, and many of the policies they have been seeking are now on the government's agenda. One issue of particular concern for Japan's neighbours is nuclear weapons. For the first time in 60 years, Japan is preparing to discuss the acquisition of such technology.
Its new Prime Minister, Shinzo Abe, has also declared his intention to change the constitution so that Japan can send troops into overseas combat for the first time since 1945. Senior officials insist the changes are to allow Japan to better meet modern demands, especially as an active member of the United Nations.
But a militarily resurgent Japan is creating nervous reactions from neighbours, who remember the millions killed in Japan's war-time expansion.
Such nationalism has already sparked street protests from teachers who are resisting orders to force students to sing the national anthem and salute the flag.
"If you look at all the laws they passed in the past three years it is preparation for war like we did 60 years ago," says Yumi Kikuchi, a writer who was attending a meeting in central Tokyo recently to protest against moves to the right.
All of this is exactly what Japan's influential and well-organised right-wing movement has been demanding for years. Using trucks with loud-speakers, the right-wingers are a menacing sight in the smart shopping districts of central Tokyo on a Saturday morning.
In February this year one of Japan's leading liberal politicians, Koichi Kato, had his house burnt down in an arson attack by right-wing extremists. " This aggressive nationalism can be appealing to people who are trying to find something and this attack is an example of the growing appeal of that right-wing activity," said Mr Kato
'Japan: Red Sun Rising" is broadcast tonight at 7.35 on Channel 4's Unreported World