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.
If anyone has any more information please feel free to comment.