that is a japanese vault that was exposed when the area was cleared and leveled to make way for a poultry. unfortunately, the bulldozer and the backhoe cannot level it. it is so hard that the bucket of the backhoe and the bulldozer got broken in an effort to destroy that cement. until now, they cannot break it.
is that the base of a corn mill .,.......made by the ones who invented the strongest cement (new yorkers) like in the footings of the empire state building 1934 ....i dont remember seeing any strong buildings in the B-29 sight photos mostly wooden ones ....remember the first invaders had 44 years with materials ,,,the second only had 3 years with no materials ....