There is only one official census medal for Japan, though there were a few censuses taken from 1920 to the end
of the war. One was taken every five years except for 1945, which was a confused time because of the end of
WW2.
The badges for the censuses were given to those who were official census takers (or somehow employed by
the census bureau). They may have conducted a door-to-door survey, but more likely the heads of the
communities gave over information to the census takers