After the Second World War, Nikkatsu (which had been primarily active in the hotel business and such) began taking steps to return to movie production under president Hori Kyuusaku, constructing Tamagawa Film Studio (in reality, Nikkatsu Film Studio) and trying to hire directors and actors away from the five companies.
As a distribution system had not yet been established, and there being little foreign money in public circulation at the time, the brokers known as "transporters" came onto the scene.
Given the demand for American films, inevitably the demand for organization of Japanese-side staff (production/scriptwriting/film development) rose; and, as at that time there were also points in which TV channels' knowhow was lacking, there became no work other than that in inferior circumstances, particularly voice acting in Japanese dubs.
[1] The popularity of television increased following major events such as the wedding of the Crown Prince (Akihito) and the 1964 Summer Olympics, and by the mid-1960s, the penetration rate reached approximately 90% for each household.
[3] A primary factor was the death of star actor Ichikawa Raizō VIII, to illness in 1969.