There are approximately three-million four-hundred thousand registered student athletes in middle and high school in Japan. Despite a large number of participants, health and safety policies for student athletes in Japan are at its infancy and there is paucity of data-driven policies to reduce catastrophic and fatal injuries from sports. PURPOSE: Describe the epidemiology of sudden death in organized school sports in Japan. METHODS: Data submitted to Japan Sport Council (JSC) Injury and Accident Mutual Aid Benefit System between 2005-2016 were retrieved from JSC website for analysis (n=1,137). Case information on fatal incidents occurred during organized school sports in middle and high school students were extracted for further analysis (n=198). Descriptive statistics related to information about activity type, sex, sport, diagnosis, and presence of on-site trained medical personnel were calculated using frequency and proportion. Sudden death incidence rates were expressed per 100,000 athlete-years and 95% confidence intervals (CI). RESULTS: Fatalities were reported in practice (n=120/198, 60.6%), scrimmage (n=16/198, 8.1%), game (n=10/198, 5.1%), training camp (n=16/198, 8.1%), and other (n=36/198, 18.2%). The average incidence rate of sport related fatality was 0.39 death per 100,000 athlete-years (95% CI= 0.31-0.47). Most fatalities were in male student athletes (n=149/162, 92%), which yielded to 7.5 times greater fatality rate in male than female student athletes (male, 0.60 death per 100,000 athlete-years, 95% CI= 0.46-0.73; female, 0.08 death per 100,000 athlete-years, 95% CI= 0.03-0.13). Baseball (n=25/162, 15.4%), judo (n=24/162, 14.8%), soccer/futsal (n=20/162, 12.3%), and basketball (n=18/162, 11.1%) accounted for 53.7% of fatalities. Sudden cardiac death (n=68/162, 42.0%), head trauma (n=32/162, 19.8%), and heat related injury (n=25/162, 15.4%) were the top three diagnosis of fatality. Only three cases (2%) reported of having trained medical personnel on-site at the time of incident. CONCLUSIONS: Sports-related fatality among Japanese student athletes was highest in male baseball players during practice due to sudden cardiac death. Almost no incidents had trained medical personnel on-site at the time of catastrophic injuries during school organized athletics in Japan.