Today I learned about hikikomori, a common phenomenon in Japan in which a person is extremely isolated from society and shut himself in his room for long periods of months to years.
In 2010 there was about 700,000 hikikomori in Japan, with an average age of 31. In most cases, these are people who are locked in their parents' room and are not willing to leave.
Japan is also talking about the "2030 problem" when the Hikomori parents begin to disappear and leave their children without support.
Source: https://en.wikipedia.org/wiki/Hikikomori