In Japan, hikikomori refers to a phenomenon of severe social isolation and confinement usually seen in young adults. Synonymous with hikikomori is the term NEET, an acronym for Not in Education, Employment, or Training, which is what most social recluses are – people who exist in solitude without contributing to a productive society.
Source:https://www.cbr.com/best-hikikomori-neets-anime/