The term hikikomori describes a specific form of social withdrawal that can be observed in children, adolescents, and young adults. Epidemiological research studies have shown that this condition is comorbid with a psychopathological disorder only in 50% of all cases. Many young people in a state of withdrawal do not show symptoms ascribable to already known diagnostic parameters. The authors, psychologist, and psychiatrist at the UFSMIA (Functional Mental Health Unit for Children and Adolescents) in Arezzo, illustrate the current debate on the hikikomori phenomenon from a number of viewpoints: psychiatric, sociological, anthropological, and psychological. On the basis of a clinical case discussed at length in this paper, the authors define their viewpoints and the strategies initiated at the Mental Health Unit in the presence of a patient displaying a state of acute social withdrawal. The multiple actions taken by the UFSMIA are combined according to the concept of modularity. Clinical experiences collected allow the definition of therapeutic protocols useful for the treatment of hikikomori adolescents. The overall objective is to promote the autonomy of the adolescent, as well as the reinforcement of his/her identity and personal resources, as well as the non-traumatic re-entry into the social context.