This chapter explores Japan’s medical and public health cooperation in the context of human development and human security. Like education, health is both instrumental and intrinsic to human well-being, in that it enables people not only to work productively but also to live lives they value. The chapter begins by contextualising health within a broader ecological and ethical framework, emphasising the shared vulnerability of humans to zoonotic diseases. Three major case studies illustrate Japan’s evolving approach. First, the Noguchi Memorial Institute for Medical Research (NMIMR) in Ghana exemplified large-scale, technology-intensive cooperation in tropical medicine, yet it also raised fundamental questions regarding the ownership and sustainability of development projects. Second, the project of the School of Veterinary Medicine at the University of Zambia (UNZA) expanded medical cooperation to include animal health, thereby linking human and veterinary sciences. Finally, the Family Planning and Reproductive Health Project in Jordan demonstrated the effectiveness of community-based outreach, empowering women and promoting behavioural change through local health workers. Across these diverse contexts, Japan’s approach shifted from short-term medical aid towards participatory institution-building. The chapter concludes that peace, scientific collaboration, and human-centred partnerships are the indispensable foundations for realising the right to health globally.