The battle against coronavirus disease 2019 (COVID-19) still continues three years after the onset of the pandemic, but there are concerns about the next emerging infectious disease. This study reports the practices during the initial response to COVID-19 on the cruise ship Diamond Princess and lessons learned from a nursing perspective. During these practices, one of the authors dealt with a sample collection team from the Self-Defense Forces and collaborated with the Disaster Medical Assistance Team (DMAT), Disaster Psychiatric Assistance Team (DPAT), and other teams. They mentioned the passengers' state and the distress and fatigue of the personnel assisting them. This revealed the specifics of emerging infectious diseases and their commonalities, regardless of the disaster. Results identified three crucial points: i) predicting the impact of lifestyle changes on health due to isolation and implementing preventive measures, ii) protecting individual human rights and dignity even in health emergencies, and iii) support for personnel providing assistance.