Term bandied about in Japan to describe adults in their twenties, thirties (or even older) still living at home with their parents. Living rent-free, it is obviously in their interests to stay, and this gives them considerable purchasing power to buy Louis Vuitton and other luxury goods.

Girls in particular are more likely to be branded as parasites, as their folks wonder when they are going to settle down with a nice Japanese man. As long as they can work they have no dependence on men, and while female emancipation in the Japanese workforce has still got a long way to catch up, progress has even been much slower in the domestic sphere. So, while Japanese men remain committed to their traditional roles, Japanese women are less attracted to the prospect of marriage (and unlike their mothers and grandmothers, will simply not endure a mediocre relationship). Meanwhile the parents, often coming close to retirement, are too nice to do anything but endure the continuous presence of their darling children while they give them a roof (and usually meals and a laundry service).

Another reason why children delay leaving home is their pursuit of dream careers, where they promise to themselves to achieve a desired job before trying to become fully independent.

The term was coined by Tokyo Gakugei University sociologist Professor Masahiro Yamada, who started off looking at the factors drawing young Japanese towards hedonism and away from any familial duties. They feel powerless to change the direction of Japan, and instead only feel loyalty to themselves.

This has become a public policy problem. Household formation generates economic activity - something Japan needs since it is still in recession. Japan's birth rate is one of the lowest in the world, and it also has a significantly large population of older persons. Japan will not have enough children to grow up to become the next generation of workers and taxpayers.