::Hikikomori

Hikikomori (Japanese: ひきこもり or 引き篭り) are adolescents and young adults that feel overwhelmed by the Japanese society, feel unable to fulfill their expected social roles, and react with social withdrawal. Hikikomori often refuse to leave their parent's house, and may lock themselves in a single room for months or even years. According to some estimates there may be 1 million hikikomori in Japan, or one out of 10 young men. Most of them are male, and many of them are the eldest son.

More at:
Wikipedia: Hikikomori
BBC News: Japan: The Missing Million