Hikikomori (Japanese: ひきこもり or 引きこもり, lit. "pulling inward, being confined"), also known as acute social withdrawal, is total withdrawal from society and seeking extreme degrees of social isolation and confinement. Hikikomori refers to both the phenomenon in general and the recluses themselves. Hikikomori have been described as loners or "modern-day hermits". Estimates suggest that half a million Japanese youths have become social recluses, as well as more than half a million middle-aged individuals.