This study aimed to clarify citizens’ issues with the current parenting support services provided by the public sector in Japan. The main objective of this study was to investigate the integration of service design methods into parenting support services. Citizen-participatory design workshops were conducted to identify and evaluate the parenting support services provided by the public sector. The design workshop results were analysed using naturalistic inquiry and classified on the basis of Stickdorn’s five principles of service design thinking. Psychological, financial, and functional issues were identified in relation to parenting support services currently provided by Japanese municipalities. First, the social structure of parenting in Japan currently causes isolation among mothers as a result of physical and psychological burdens. Mothers often do not know where or how to ask for help regarding childrearing. Thus, it is important that people are aware of the services that are available for parenting support. It is also necessary to design these services so that people can learn about, choose, and access them. Second, it is necessary to investigate how much financial support is needed in more detail, as well as elucidating when, or whether, the needs of users can be better met through means other than financial support. Third, a failure of digital transformation is a cause of difficulty in understanding available parenting support services for guardians. Finally, the results suggested that guardians often lack co-creative partners and holistic perspectives on parenting support services.