Un-rebuildable property means the property you can’t build a new house on the land.
Even if you make it to vacant land, you can’t build new house on the land. There are many reasons why you can’t rebuild new house, many reasons are not face to public road width 2M. According to building standards Act, the property needs to face 2M width if you want to build a house. In Kyoto, there are many narrow alleys and it is still exist old houses. So in Kyoto, there are a lot of un-rebuildable properties.
If it’s un-rebuildable property, it’s nothing worth to buy. Do you really think so? Even you can’t build new house, if you maintain well and renovation, you can live for a long time.
1) It’s cheap. So you can think it for second house, retirement house. Normally the price is about half price)
2) Compare to around property, the property tax is pretty cheap. Also property acquire tax is cheap.
3) The price is cheap. So you can expect high return investment if you rent.