What is the difference between Japanese citizenship and Japanese nationality?

Question:

Also how does this relate in terms of the residency registrations system and the koseki registration system? Can you be in the residency registration system if you are not a citizen?

Answer:

To be accurate, there is no difference between the 2 in Japan. Or we don't have "citizenship" concept here.

>Can you be in the residency registration system if you are not a citizen?

No. Only those who have citizenship/nationality would be in the registration.