Objectives: Hikikomori is commonly defined as a social condition in which individuals avoid social participation and relationships beyond their family members by confining themselves to a room or their house for 6 months or longer. Hikikomori has been predominantly considered a problem among young people; however, as the population is ageing, hikikomori has also emerged as a social issue among adults. Nevertheless, no comparative studies have examined the differences in the factors associated with hikikomori among teenagers/young adults and middle-aged/older adults. Thus, this phenomenon has not been thoroughly examined, and it remains unclear whether the risk factors vary between teenagers/young adults and middle-aged/older adults. Based on the Japan Cabinet Office’s definition of hikikomori, this cross-sectional study evaluated the prevalence and related factors of hikikomori among the working age population (15–64 years), utilising univariate and multivariate analyses. The study also compared differences in the prevalence of and factors related to hikikomori between teenagers/young adults and middle-aged/older adults. Methods: We distributed self-administered questionnaires to individual participants and their families between 24 December 2020 and 18 January 2021. Results: Data from an anonymised sample of 3,092 individuals (split into two groups of 15–39 and 40–64 years) were subjected to analysis. The results revealed a hikikomori prevalence of 2.3% in the target population; the prevalence rate was 2.12% among individuals aged 15 to 39 years and 2.42% among those aged 40 to 64 years. The analysis demonstrated strong correlations between hikikomori and several factors, including unemployment, truancy, a history of psychiatric consultation or hospitalisation, being male and the absence of ibasho, which is defined as a place where individuals can feel peace, security, acceptance and belonging. The factors associated with hikikomori differed between teenagers/young adults and middle-aged/older adults. Conclusion: Our findings, thus, contribute to existing research by providing a comparative analysis of risk factors across different age groups.
