The phenomenon of “hikikomori” is characterized by spending most of the day in one room, visibly avoiding social situations and interpersonal relationships, and leaving one’s room only at night so as not to be noticed by others, and spending a lot of time surfing the Internet or playing video games. Although first described in Japan, cases have been described from around the world. Studies on hikikomori available in the literature indicate a wide range of disorders diagnosed in this group of patients such as anxiety disorders, personality disorders, mood disorders, and psychotic disorders. However, it is most often observed with ASD (autism spectrum disorder). The aim of this study is to consider hikikomori as a specific presentation of psychotic decompensation in people with ASD. In the case of a 10-year-old boy with ASD, sulpiride brought an improvement in social withdrawal, which, together with the symptoms presented by him, may indicate the possibility of psychotic decompensation in the form of hikikomori. Due to the lack of therapeutic guidelines for the management of people with hikikomori, this may be a valuable guideline for the implementation of appropriate pharmacotherapy by clinicians, in which attention should also be paid to frequently occurring other psychiatric disorders.