[elldoubleyew]

>they ask you to

My understanding is that they can't really enforce this. You can still hold multiple citizenships even if its against the rules.

[throwaway2037]

I have seen this with dual nationals by birth in Japan -- both Japanese and something else. By law, they are required to make a choice at age 20. However, the "by law" part is very hard to enforce if their parents registered for nationality in the non-Japan country after applying for nationality in Japan.

Ref: https://en.wikipedia.org/wiki/Japanese_nationality_law#Dual_...