Just received a reply from my friend:
Wow! It is very beautiful piece...
Japan's pottery art "developed?" after war with Korea because they got lots of good Korean pottery artists in the war.
They had pottery art, but it was not as good as Korean or Chinese one, but Japanese gave very good support for those Korean pottery artists to develop good pottery.
In mid 18c, they finally developed "Arita" style which your friend have.
Also, China which was famous and biggest pottery art county had a big war in their nation around mid 17c. They had a hard time to develop other things little while.
So European got pottery business with Japan. Then Japan became an important and famous country for pottery business with "Arita" style... It also gave influence for impressionism in Europe. It also lead Japan's economy and power from 19c...
I think it could be 19c piece because the style began from Mid 18c then it became famous 19c...
p.s. it is based on history book, so if your friend is interesting. They can look for "pottery war between Korea and Japan" or " Arita" style...