ABSTRACT
The koseki system has since early Meiji exerted a profound influence on the Japanese civil law system. This chapter examines how household-based registration shapes modern Japanese society through a principle called jus koseki. It explores the influence of the koseki system in relation to Japanese citizenship. The principle of jus koseki is the right that derives from registered household membership. According to Tashiro, the original Japanese that existed immediately prior to the enforcement of the 1899 Nationality Law were those who were nationals prior to its enforcement and they emerged from the residents-as-nationals idea. In the Edo period, the smallest unit of registration was the village. The principle of naturalization through marriage and adoption also facilitated transfer between the two-tiered naichi and gaichi Japanese citizenships that emerged in the colonial period. Old koseki are in principle koseki that are more than three generations old, at which point they must be considered documentation confirming Japanese citizenship.
