South Korea itself can serve as an example.
But some neighbors like China may be afraid of a strong and unified and prosperous Korea.
A unified and prosperous Korea would probably be a bigger economic power than Japan and somewhat like China.
Years ago Singapore had a horrific drug problem. They solved the drug problem. If you were a drug user you went to jail for a short period of time that was unpleasant in the extreme. If you sold drugs you were hanged. Singapore does not have a drug problem today.
This begs the question of whose laws in relationship to drug use is better, USA or Singapore? Today drugs in the USA cause untold grief, violence and death among innocents and criminals alike. I vote for the Singapore solution.
China wants to control the World and you can’t control the World if you free countries you control ,LOL
Certainly the Japs are terrified. Probably more than the Chinese and probably for reasons that are not so unrealistic. We think of history in 24 hour bytes. I don’t think they do over there. A unified Korea in an ancient historical sense is likely not going to end well for Japan down the road somewhere. Those people think of history in terms of millennia not decades.