Providing a continuum of care (CoC) is important strategy for improving maternal, newborn, and child health (MNCH). Japan's current very low maternal and infant mortality rates suggest that its CoC for MNCH is good. In this paper, we attempt to clarify how CoC and low mortality rates are being maintained in Japan, by examining the entire MNCH service provision system. First, we examine two important tools for integrated service provision, the Maternal and Child Health (MCH) Handbook and registration of pregnant women with local governments, both introduced in 1942. Second, we explore the incentives provided by the MNCH system that prompt actors to participate in it. The three actors identified are service users (e.g., mothers and babies), medical professionals, and local governments. Through system design, all three actors benefit in ways that incentivize them to use MNCH services, which consequently connects service users with resources: all service users regardless of financial status, nationality, and location can receive free MNCH services such as antenatal care, assistance with childbirth, postnatal care, and immunizations; using the handbook, service users obtain health information, and medical professionals obtain the health records of pregnant women and their children as well as access examination fees from the local government by submitting vouchers in the handbook; local governments can then identify pregnant women for follow-up and provide health information and administrative services. As a result, the coverage rate of the MCH Handbook has reached 100% and MNCH services coverage could potentially reach the same level.