I finally saw the prof present some of his work and it goes back to the Perry exhibition in 1853 or whatever year it was. He had some paintings from japan of the event, and one is of a minstrel band, playing banjos and mandolins!
Denis also told a great story about the first time he heard a bluegrass band in Japan. He said they had the perfect Appalachian vocals in their songs, the perfect accents, but when he went to talk to them after - they knew not a word of English! But the scene has a strong emphasis on reproducing the sound and lyrics perfectly. He likes to improvise, which clashes with his Japanese musical colleagues style of faithful representation…