Some time ago, I mentioned the house that was torn down in my neighborhood and how fast they were doing it.
Then, nothing much happened for a few weeks although I have seen tons of concrete being infused into the ground, and I have also spoken to the man who has measured the plot and set up the outline of the new house to be built. Funny talking about Pythagoras in such circumstances…
Then, maybe two weeks ago, builders started with the foundations. Foundations nowadays are made of concrete, of course, and they are essentially a flat slab under the whole house with little walls on which the future walls of the house will rest, maybe 40 cm high, not more. In this basement floor and walls, pipes are laid for water and sewage, and on top of that comes a wooden construction that essentially is the floor of the ground floor. Note that I have not seen any insulation being installed between the raw concrete and the wooden floor, but to be fair, I was not there standing and watching all day.
Two days ago, with lots of hammering, they started building the house on top of the foundations. I have heard some hammering and the occasional drilling, but not much more noise throughout the day as it would be usual in Europe. As I had suspected, the house is a fully wooden construction, and yesterday night, the frame was finished and looked thus: 
Take a closer look, do you notice the numbers on the timber? Every wooden beam has its individual number, obviously the construction plan contains the same numbers. Thus, the whole house can be prefabricated somewhere off site, and only needs to be assembled with the right pieces in the right place and order. No wonder they can be so fast in building a house in Japan! 
To be quite honest though, the whole thing appears to me rather flimsy. Clearly, the house will gain further strength by adding the walls, so maybe proper joining is not really necessary. Still, I have the impression a really big earthquake and these things are flattened in a heartbeat. Not like that 500-year-old farmer’s house I have seen that survived a very strong earthquake practically intact – albeit 1 metre off its original location…