In this work, we suggest that children’s social withdrawal might be a precursor of Hikikomori, a phenomenon observed among adolescents and young adults. Hence, psychotherapy interventions with preschool children showing signs of social withdrawal might play a critical role in Hikikomori prevention. This paper presents the case of a five-year-old child treated with intensive psychoanalytic psychotherapy who began therapy due to his refusing to go to school and exhibiting isolating behavior from other children. Among other symptoms were regression, emotional tension, nightmares, and nocturnal and diurnal enuresis. Moreover, the relationship in the family was difficult, both between the parents and between the parent and the child. The intensive psychoanalytic treatment involved three weekly sessions for about a year, followed by six months with one weekly session. Besides illustrating the therapeutic process through clinical vignettes taken from the sessions, this paper also provides clues on how early social withdrawal can contribute to the construction of internal personality organizations that lead to social withdrawal up to self-reclusion (or Hikikomori).