As indoor life became more comfortable, entertainments such as renga (a group of more than ten people gathered and composed a series of linked poems), chakai (tea gatherings) and ikebana (flower arranging) became popular in the Muromachi period. The collecting of art and craft works from China (karamono) and the display of these objects in living rooms was also very popular. So a place to display the karamono became necessary.
It was customary to hang a Buddhist picture on the wall and put three utensils (mitsugusoku) , an incense burner, a flower vase and a candle stick on a table before them for worship. Finally this structure was built into the room and called the oshiita. This became a place to display things.
Buddhist priests used to make a study space protruding from the side of the house to let in more light. This was called a tsukeshoin. They also made shelves (tana) on which to put volumes of sutras and other books. The tsukeshoin and tana were also used as places to display things.
Finally oshiita, tana and tsukeshoin were built into most zashiki rooms and used as places to display karamono. Part of the room was built one level higher for people of high status to sit on, and this was called the toko (alcove). The oshiita, tana and tsukeshoin were built on the toko, and a house constructed in this way, in which things could be displayed and guests received, was called shoinzukuri. The shindenzukuri residences of the Heian period developed into the shoinzukuri style as an improvement in lifestyle. With the realization of shoinzukuri, the culture of the zashiki (tatami mat room) was born. This became the basis of the Japanese lifestyle.