OBJECTIVE: Hikikomori, from the Japanese words 'hiku' (to pull) and 'komoru' (to 
withdraw), is a clinical condition in which a subject locks himself/herself into 
his/her own house for more than 6 months. This condition is becoming relevant in 
Japan and other Asian countries, with new cases emerging in Europe and a steep 
increase in its incidence.
METHODS: In this article, the various psychopathological and diagnostic 
hypothesis and the different criteria proposed by the various authors have been 
analysed and compared, paying attention also to the new studies conducted in 
Europe and to therapeutic perspectives that are opening up for its treatment.
RESULTS: Numerous hypothesis have been put forward for the genesis of 
hikikomori, in particular, the hypothesis of a behaviour seen as a dysfuncion of 
the family system or as a result of our current modern society. Furthermore, 
this behaviour has been compared to other conditions such as internet addiction 
and a specific form of depression called Modern Type Depression (MTD).
CONCLUSIONS: Hikikomori could represent the clinical answer to a social 
evolution, similarly to other phenomena such as binge behaviours and use of 
psychoactive substances. Further studies are needed to clarify diffusion, 
diagnosticassessment and differential diagnosis.Key pointsHikikomori is now 
considered a contemporary society-bound syndrome linked to modern society 
changes.Hikikomori might be a coping strategy to avoid relationships, social 
judgement and possible failures.Hikikomori might represent an extreme suffering 
that needs to be identified early: it is linked to severe form of modern type 
depression and it is a risk factor for suicidal behaviours.It is important to 
inform and sensitise communities about hikikomori to assure early 
interventions.More clinical studies are needed to define a unitary and specific 
model of hikikomori and to structure focussed interventions.