Japan Simple Life

I'm going to be in Japan for all of Golden Week. My girlfriend and I will be spending 2 days/1 night in Chichibu, and I'm sure she has some other...

Any ideas what the thing circled in the pic is used for?

So, what happens when a new apartment building (six units @ around 50 million yen each) is 30cm too close to the boundary?
Looks like they are going...