Earlier this week, as Japan was preparing to mark the historic abdication of one emperor and the enthronement of the next, a small group of people gathered on the edge of Tokyo. "Let's not forget the war responsibility of the emperor," the protesters chanted as they marched towards a park.

The group, mostly grey-haired, belong to a small but vocal minority of Japanese people who think the time has come for the age of emperors to end.

Japan claims to have the world's oldest continuing monarchy. According to legends, the royal family are descendants of the sun goddess Amaterasu. Until the end of World War Two, emperors were seen as living gods. Han Tennosei Undo Renraku Kai (Anti-Emperor Activities Network), or Hantenren, have been calling for the abolishment of the monarchy for more than three decades. They say it's the only way for Japan to atone for the wars waged in the name of the emperor in the 1930s and 40s. "The war hasn't been put to an end properly," Nomura, a Hantenren member, told the BBC. He asked to be referred to only by his surname, for fear of attacks by right-wing groups.