As youngest of the pre-war companies, Daiei emerged into the post-war era without a chain of theaters, and since it had been organized at a time when distribution was in the hands of a monopoly, there was no opportunity to line up contracted theaters.
Now definitely on top, Daiei set what shortly was to become a pattern, representing as it did the perfect compromise between the exoticism which the studio believed the West hungered for and the mediocrity which it was thought that Japan would happily consume.
Daiei was revived in the summer of 1974 under the presidency of newspaper publisher Yasuyoshi Tokuma.
Historically however, prior to the Meiji Restoration, era names were changed on many different occasions such as celebration, major political incidents, natural disasters, and so on, but the emperors posthumous name never took the name of an era.
Incidently, on modern official papers, those who were born prior to the Meiji era did not write the era name in which they born, but wrote Edo period (though now no one born over 130 years ago in that time period is still alive now).