Fukushima Prefecture salient

The Fukushima Prefecture salient, known colloquially as the "umbilical cord" (Japanese: へその緒県境, Hepburn: Hesonoo Kenkyō) or the "appendix prefectural border" (盲腸県境, Mōchō Kenkyō) is a panhandle and a hiking trail in Fukushima Prefecture in Japan. It consists of a narrow strip of land which lies between Yamagata Prefecture and Niigata Prefecture, passes across the summit of Mount Iide, and ends on the summit of Mount Onishi.

Source: Wikipedia — Fukushima Prefecture salient (CC BY-SA 4.0)