This study quantitatively evaluates the impact of the Tourism Nation Promotion Project on tourism demand. Data were obtained from Japan Tourism Agency’s quarterly survey from 2010Q2 to 2015Q4. Cox and zero-truncated negative binomial models and difference-in-differences approach were applied to analyze tourism demand and the project’s impact on inbound tourists’ length of stay and expenditure in Japan. Empirical results showed a positive and significant average treatment effect on length of stay and expenditure for tourists from Australia, China, Russia, and Thailand. These findings indicate that the Japanese government should use differentiated strategies considering different nationalities’ characteristics to attract foreign tourists.