Dear Popo, thank you very much for your heart warming videos. I started to watch them today. I enjoy them very much. At the end of this video you wrote you wonder how long your son can keep Japanese passport. Your children can keep Japanese passport and French passport forever. They were born as Japanese and French. It is their birth right to keep both citizenships. Our daughter, 24 years old, keeps passports from Mama (Japan)and Papa's countries (USA and Austria). I did not know this fact in the past. Please investigate it.