Hikikomori

Hikikomori (lit. "pulling away, being confined," i.e., "acute social withdrawal") is a Japanese term to refer to the phenomenon of reclusive adolescents and young adults who have chosen to withdraw from social life, often seeking extreme degrees of isolation and confinement due to various personal and social factors in their lives. The term "hikikomori" refers to both the sociological phenomenon in general as well as to individuals belonging to this societal group.
-- Wikipedia