How gender equality and equity relate to fertility becomes a central concern for population scholars as well as policy makers in developed countries. Both the theories and empirical studies from western countries suggest that achieving higher levels of gender equality or equity within the household can lead to higher fertility in the societies where gender gaps in education and employment are small. However, previous findings on this topic are either theoretical or being based on cross-national comparisons, and their focus is largely limited to western societies. Japan is a country where the economy is highly developed, while the levels of gender equality is one of the lowest among high-income nations. The country’s population started to decline since 2011 due to the prolonged period of the lowest-low fertility. In 2012, however, Japan’s Prime Minister Shinzo Abe and his cabinet announced that expanding opportunities for women to join Japan’s labor force, “womenomics”, is one of the key pillars in their economic revival strategy and started several policies to change Japan’s gender climate. Our study provides new evidence from Japan about how associations of gender relations with parity progression are affected in the time of changing gender norms. We use population-based panel data from the 2001 and the 2010 cohorts of “Longitudinal Survey of Newborns in the 21st Century”. Our study examines associations of couples’ participation in both market labor and domestic work with transition to the second and third births by employing event-history analysis. The associations are compared between the observation periods of 2001-2006 and 2010-2014 as the survey follows the households of newborns born in 2001 and 2010 in Japan. By taking an advantage of this unique survey design, we evaluate how the associations change between the two periods; one period with less gender equality and another with better.