In 1990's, FURUTA was deeply involved in "Tsugaru Sangun-shi" (The history of the three counties in Tsugaru region), and it is strongly suspected that "Tsugaru Sangun-shi" was gisho (apocryphal book).
1990年代に『東日流外三郡誌』に古田が深く関与し、同書が偽書であることが強く疑われた。