Chashitsu Tetsu (Tetsu Teahouse)
by Terunobu Fujimoir and Nobumichi Ohshima (Ohshima Atelier)
I know very little more about this than the information contained in the caption – that it is a Japanese tree house set among the cherry blossoms, effectively combining two Japanese traditions – drinking tea and admiring the cherry blossoms. It is not clear how you get up there from the low steps below.
I think it dates to around 2006.
This appears to be another variation on the same theme.
If anyone has any more information please feel free to comment.
The Folly Fancier 
These are by Terunobu Fujimori, a japanese architect who builds a lot of them.
They’re Baba Yaga houses! Wikipedia that noise.