"The native Japanese have lived as a single ethnic group for nearly 1000 years and it will be a difficult task for them to build friendly relationships with other ethnic groups."
Source: The Future of Japan’s Immigration Policy: a battle diary
By Sakanaka Hidenori
Introduction by Andrew Taylor and David McNeill
Translation by Andrew J. I. Taylor
http://www.japanfocus.org/-Sakanaka-Hidenori/2396