How are Japanese property taxes appraised? Do they look inside the house, and if so, what counts towards property values?

For example, if I build a giant double-helix stairway with marble columns inside my house, but the outside looks like an average 3LDK, is the man going to find out?

Or another example, what if I fill my house with nice marble statues that are technically moveable to a new location. Do movable things count towards the property value?