Are Japanese last name same from a heritage to another heritage? If a Japanese women surname example name Hamasaki marries a man with surname Tanaka, does it mean the women has to change her surname to Tanaka? What about if a foreigner marries a Japanese, does the women surname has to change to the husband's surname?
The majority of Japanese women (95.9 per cent, according to this article) adopted the family name of their husband, although the Civil Code only stipulates that they have to share the same surname. Therefore, they could choose either the wife's or the husband's family name.
On 13 February 1875 (明治8年) it was officially decreed that all Japanese must adopt surnames. An additional decree from 17 March 1876, mandated that spouses must both keep their original family (maiden) names. It was in the year 1896 that Japan returned to the old civil law that obligated spouses to share the same family name. Article 750 of the revised Civil Code (1947) stipulates that a couple should use either the husband's or the wife's surname.
Modern Japanese names (日本人の氏名 nihonjin no shimei) usually consist of a family name (surname), followed by a given name. This order is standard in Asian countries, while middle names are not generally used. Japanese names are spelt in Chinese...
jref.com
In the case of international marriage, spouses can either share the wife's or the husband's surname or keep their original family names.