The building like a teahouse on the mountain pass is Shoka-Tei.
This teahouse also has thatched roof. It is a little simpler than Shokin-Tei. This is a quiet place enough for you to look over Katsura Imperial Villa since it is on the hill.
This is the inside view. There is a spot on the wall as it proves it has endured snow and wind of many years. It is really quiet. You can go into it to sit down and look over the green view outside through a lattice window.
It is written by someone noble or famous? I am not familiar with calligraphy and just thought the letters are square.
A teahouse on the hill. It is built on the highest point in the garden and it has unhusked poles for thatched roof. The view seen through a bamboo lattice window in the South has a flavor of deep mountain and retired and quiet state. (according to the brochure which Imperial Household Agency published)