It was hard to find because it wouldn't come up on my iPhone map. I eventually found my way to an imposing gate with barbed wire (and someone's jacket) on the top. However, it was pretty easy to squeeze around the side. From videos I've watched you used to be able to drive right up, but that was no longer the case.
The approach road was about half a kilometre up a steep hill angling around to the left so you couldn't see anything until you appeared in the car park at the top. The first signs of decay I saw were the missing manhole covers, which could have been pretty treacherous in the dark.
I had watched a few YouTube videos of what it used to look like (here's a good one), but aside from the church and the hotel there was almost nothing left. The whole courtyard at the bottom (including the mammoth building) had been bulldozed into heaps of rubble, as had the buildings in the top part and the walkway down to the bottom. The church and the hotel were interesting, but pretty much everything that could have been taken had been, to the point where even the ceilings had been ripped open, spewing insulation on to the floor.
While it was interesting and it satisfied my curiosity, there was so little left that it barely justified the three hour drive from Nagano City where I live and I wouldn't be inclined to go again. It was clearly in the middle of a process of at least partial demolition, and there was very little left to identify it. I saw no signs or maps, for example. It was a fascinating trip, but to be honest I had as much fun swimming in the sea on the way home.
The courtyard from the former carpark
What used to be (presumably) the ticket office and gift shops
The back of the burned out hotel
Inside the church
The last visitor...?
The gutted lobby
The other side of the hotel
What used to be the lower courtyard of shops and display rooms etc.
Now reduced to rubble
A child's toy lying on the road in front of the rubble
Rubble from the ceilings in what was once a ballroom
Looking out from the hotel towards an overgrown golf course
One of only a couple of bedrooms that weren't gutted by fire
All that remained of the mammoth
The entrance gate, complete with jacket
Enjoyed a nice swim at this patch of nearly deserted beach near Joetsu on the way back
August 17th 2015