關東平原
The MTL goes from Shimonita in Gunma Prefecture to the Hiki hill district in Saitama Prefecture, and then continues down to the Kantō Plain. In the central Kanto Plain, boring tests have shown that the MTL lies 3000 meters beneath ground level in Saitama Prefecture. It is not clear where the MTL goes from there, but it is thought that it passes beneath Kashima or Ōarai on the Pacific coast in Ibaraki Prefecture.