While the global population keeps growing, Japan is facing a very different future which could see their population shrink by a third in just 40 years. One reason is that the Japanese are having fewer babies.
As part of a journey across Japan to find out why men and women are drifting apart and having far less sex than most other nations, Anita Rani explores the Otaku culture - a world of nerds and geeks obsessed with computer games and Manga cartoons - which has led many Japanese men to withdraw from the whole dating game.
She meets two men in their late thirties who have been dating virtual teenage girlfriends for years as part of a role playing game. Worlds apart from the fantasy girls of the Otaku culture, Anita also meets working professional women who struggle to work and have children in a society still dominated by traditional gender roles.
Low birth rates, combined with longer life expectancy, is inevitably leaving Japan with an old and rapidly aging population. Already a quarter of Japanese people are over 65 - and 50,000 are over a 100 years old. Anita visits a group of cheerleading pensioners and a prison with a wing especially designed for pensioners and looks at how the population trends in the country add to a debt problem worse than that of Greece and an uncertain future for a country that still is the third largest economy in the world.