Semi outdoor space has been important in Japanese architecture since old time.
It was "DOMA 土間" in farmer's house, or It was "Engawa 縁側" and other space under a roof.
"DOMA 土間" was a working space for farmers at night, in rainy day or winter.
A floor of DOMA was made as "TATAKI 三和土", the floor level was lower than other floor in house but as same as outside. There were a part which was connected to outside, sliding doors were installed to the opening to inhabitant could connect DOMA to outdoor space.
"ENGAWA 縁側" is still popular now in Japanese house.
It was already exist in palatial architecture in Heian era (平安時代 794-1185), usually ENGAWA was made along with the architecture's outline under the roof and it was separated from inner space with Shoji 障子, SUDARE 簾 or MISU 御簾.
ENGAWA had functions, functioning as buffer space to prevent strong sunlight in summer, and tiny event space for enjoy moon light, music recital and so on.
*" Genjimonogatari emaki" picture scroll of a tale of Genji.