Professor Iwashita was awarded Osaragi Jiro Prize for Commentary by Asahi Shimbun for his sensational book in Japanese Northern Territorial Issues: Neither Four nor Zero, nor Two (Chuokoron-shinsha, 2005). This prize was established in 2001 and has been awarded to the books that contributed greatly to the activation of the world of criticism and directed the course for the 21st century. His book was highly evaluated by the selection committee as challenging one of the most difficult issues in Japan’s diplomacy.