COVID-19 brought the threat of unknown viruses to global attention. This documentary, a collaboration between Japanese and French broadcasters, explores what's necessary to prevent another pandemic. We follow experts known as "virus hunters," working all around the world in an effort to stop the next pandemic. In part two of a two-part series, we learn the importance of protecting biodiversity. This connects to a concept called "One Health," which involves treating human, animal and environmental health as a unified whole. We also investigate whether COVID-19 is being transmitted to animals in Japan, and hear about the risk of new infectious diseases within the country.