system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why doesn't Japan allow dual citizenship?

My mother is Japanese, and my father is British, meaning I am a citizen of Japan, and the United Kingdom. Under current Japanese law, I will need to give up my My Japanese citizenship or my British. I would be really upset about giving up either citizenships. Since Japanese is in Demographic Transition stage 5, and the population is decreasing why doesn't the Japanese government allow dual citizenship?
gpt
to put it in simple words:

A government/country is essentially nothing without it's citizens, so they want to keep you.

Another reason is that it's an awful lot of bureaucracy if you have multiple citizenships and travel around and something happens etc.

Actually being allowed to have multiple citizenships is is the exception.