One morning in February, the government personnel department began an experiment in a nondescript building in a Tokyo residential area that could end up rewriting the rules of the nation's powerful bureaucracy.

For the first time, it invited 19 women from different ministries to an all-female training course designed to groom them for senior government positions. The four-day program inspired a 30-page blueprint, submitted to Deputy Chief Cabinet Secretary Katsunobu Kato, on how to fix a system that keeps government staff at work till late at night, sacrificing family life.

"We shared each other's sufferings, fears about our future, guilt about putting the burden on colleagues" when we left on time to care for children, said Noriko Kawamura, 38, an assistant manager at the health ministry. "We began to realize that it was no good just grumbling about it, we had to do something. I never thought it would turn out to be such a big thing."