What modern prefecture does the ancient Japanese place name 'Wanokuni' correspond to?

Kunihide Kunitachi is my best friend.

I have been to the Republic of Vietnam.

The system of provinces was a part of the ancient political system in Japan.

He is a perfectionist, so he is very strict about his work.

He publicly acknowledged that he is a homosexual.

He always looks at things like a pessimist.

He is always an optimist, believing in a bright future even in difficult situations.

He identifies himself as an atheist.

He is the intellectual leader of our team, always providing new ideas.