Contemporary major Japanese firms recruit new graduates and promote from within, providing a rare example of the “ports of entry” policy, and were once recognized as innovative organizations. This microanalysis of a steel company in the 1930-60s shows that 1) the internal labor market had been enhanced, but 2) mid-career recruiting was active and employees’ fertility decision depended on previous experience as well as tenure by the 1960s, while 3) the return on education surged and in-house training was linked to educational background from the 1950s, indicating that extended schooling replaced mid-career experience after the 1970s under technology-education complementarity.