Japan has experienced pronounced aging of its population, and now has the highest proportion of elderly adults in the world. However, few projections of Japan's future demographics go beyond estimating population by age and gender to forecast the complex evolution of the health and functioning of the future elderly. This study adapts to the Japanese population the Future Elderly Model (FEM), a demographic and economic Markov microsimulation model that projects the health conditions and functional status of Japan's elderly population in order to estimate disability, health, and need for long term care. We develop the model based on the recently released multiple waves of the Japan Study of Aging and Retirement (JSTAR) survey, the Japanese version of the Health and Retirement Study-like family of internationally comparable surveys. Using detailed data on a panel of Japanese aged 50-75 starting in 2007, we tailor the health transition matrix of the FEM model to the Japanese context, estimate conditional mortality probabilities consistent with Japanese national vital statistics, and use a state-transition Markov model to project trends in the disability and functioning of Japan's future elderly population.