The underground movement was started

about 1700.
Under the reign of Queen Anne.
There was not any learning technique of foreign languages such as today's electromagnetic magic of the pronunciation.
The youths of about twenty who were being shipped were demanded to be speakers of Tohoku dialect, for example, on the spot as 　　　natural as native speakers.
How on earth can it be attained?
By only one way.
You could not be such a natural speaker as the youths even if you graduated from the Language Department many times.
Then, how could the youths be native speakers?
From the start, they must have been born in a maternity home and brought up in a nursery with some Japanese speaking Tohoku　　　　dialect, or else whoever could be a Tohoku dialect Japanese whom no man might have suspected as an alien?
So many babies of Asien and European parentage may have been born successively about 1700.
1720, they became twenty years old.
A fully prepared plan and its energetic going on without a break can be supposed.