YOU SAID:
I have been to Nippon a couple of days before.
INTO JAPANESE
私は数日前に日本に行ったことがあります。
BACK INTO ENGLISH
I have been to Japan a few days ago.
INTO JAPANESE
私は数日前に日本に行ったことがあります。
BACK INTO ENGLISH
I have been to Japan a few days ago.
You should move to Japan!