By using a unique data set of academic economists in Japanese universities, we conduct the first detailed study of gender differences in the duration of promotion within Japanese academia. We employ a duration model that simultaneously allows: a non-parametric estimation of the baseline hazard function; a non-parametric unobserved heterogeneity component; and the estimation of parameterized coefficients for the observed explanatory variables. Our results show that there are no gender promotion differences, after controlling for personal, job, institutional, human capital characteristics, and unobserved heterogeneity. Our results contrast with the results of previous studies which consistently report substantial gender promotion gaps within US and UK academia. We show that age and education are the most dominant determinants of the survival probability of promotion to full-professor, with minimal rewards given for higher research output. Although the effect of age is not large enough to warrant the conclusion that promotion within Japanese academia is automatically done based on age as it is commonly believed by Japanese academics, a heavy emphasis on objective factors such as age and education may be one reason for why there are no gender promotion differences.