Supplementary Provisions, Article 9Special Provisions Concerning Reservation of Nationality Pertaining to a Child of a Person Who Acquired Nationality
第九条（国籍を取得した者の子に係る国籍の留保に関する特例）
For the purpose of the application of Article 104 of the Family Register Act in the case where, because the father or mother has acquired Japanese nationality retroactively as of the time of the prior notification through the application of Article 2, paragraph (1) and the proviso to paragraph (3) of the Supplementary Provisions, a child born on or after the time that father or mother acquired Japanese nationality and before the time of the notification under paragraph (1) of that Article comes to be subject to the application of Article 2 and Article 12 of the Nationality Act, the term "the day of birth" in Article 104, paragraph (1) of the Family Register Act is deemed to be "the day of the notification under Article 2, paragraph (1) of the Supplementary Provisions to the Act Partially Amending the Nationality Act (Act No. 88 of 2008) made by the father or mother (or, in a case where that notification is deemed to have been made under Article 3, paragraph (1) of the Supplementary Provisions to that Act, the day that Act comes into effect)".
父又は母が附則第二条第一項及び第三項ただし書の規定の適用により従前の届出の時にさかのぼって日本の国籍を取得したことによって当該父又は母の日本の国籍の取得の時以後同条第一項の規定による届出の時前に出生した子が国籍法第二条及び第十二条の規定の適用を受けることとなる場合における戸籍法第百四条の規定の適用については、同条第一項中「出生の日」とあるのは、「父又は母がした国籍法の一部を改正する法律（平成二十年法律第八十八号）附則第二条第一項の規定による届出の日（同法附則第三条第一項の規定により当該届出をしたものとみなされる場合にあつては、同法の施行の日）」とする。