After the treaties between Japan and America, England, the Netherlands, France and Russia, in 1859 the port of Yokohama was opened for foreign merchants. Since there were exceptionally little Western women after the opening of this treaty port, the authorities installed a brothel quarter. But the high infection risks made the resident foreigners cautious. They started to contract girls from local merchant families to stay with them, as if having a "marriage on time". Often out of these relationships children were born, for whom reportedly especially the Dutch and German foreigners felt deeply responsible. The Dutch merchant Rudolf Adriaan Mees had two successive Japanese women Okino and Mai, with whom he had two sons. Their case can be considered representative for an intense cultural interaction between two extremely different cultures at the beginning of the modern era in Meiji Japan.