Born a living god, Hirohito became a marine biologist and botanist and published nine successful books with titles such as Some Hydroids of the Amakusa Islands
and The Crabs of Sagami Bay.
Both works present the women of the Amakusa Islands who left to work overseas as products of chronic poverty.
Despite the difference in the conclusions, both interpretations present the amakusa onna/karayuki-san as a phenomenon confined geographically, in terms of their origins, to the Amakusa Islands. This automatically classified the karayuki-san as a minority, an abnormality, existing on the periphery of the assumed norms of mainstream society and history.
Both ascribe a very specific and historically limited identity to the karayuki-san, as a phenomenon confined to the Amakusa Islands. This specific, constructed identity also acts as a guarantor against other possible explanations of who and what the karayuki-san were.
The Amakusa women's "physical constitution toughened by hardship" made them able to "adapt to different climates and topographies," almost as if "natural." The nature of Mori's empirical evidence, and the way he utilizes it, present the karayuki-san as being specific to the Amakusa Islands. The women are depicted as objects possessing certain qualities that serve as markers of their true individuality, as distinguishable from other women.
Contrary to Mori's argument, the practice of women migrating overseas was not confined to the Amakusa Islands. For example, by the middle of the Meiji period, in all the open ports of Japan there existed kuchi-ireya (employment agencies).