Kekkai indicates a border used for partitioning a space.

However, a Japanese word “Kekkai” has two meanings; not only “partitioning a space” but also “connecting different spaces each other”, which is a great feature of this word. That is to say, Kekkai is a definite border which divides a same space into sacred and profane areas, and at the same time, it serves also as a fuzzy partition that each of the areas can feel a loose sense of unity so that the atmosphere may be known to each of the areas.

Japanese people, who had been an agricultural tribe, have even presently believed the Shinto's polytheism (Yaoyorozu no Kami) continuously from the ancient times, that adorable gods are immanent in various places around them in the world of nature (all creation). Later, they came to include the living god of the imperial family, which had been a governmental object, also as a worship object, not only the world of nature. Also, being affected by this attitude, Japanese people have been made to think a place worshiping respectable people including ancestors as a sacred place. “Kekkai” is a fuzzy border between such a sacred area and profane area.

The examples of Kekkai can be seen in the Shinden-zukuri, a style of architecture for aristocrat’s residences in the Heian Era, more than 1000 years ago. The aristocrats who lived in the Shinden-zukuri residences had been providing “Shitsurai”, the rituals where inside of the rooms was decorated with seasonal materials for expressing their gratitude and hospitality to visitors at the turns of the seasons, etc.

Those days, Shitsurai indicated the furnishings described also in the Tale of Genji, a novel in the Heian Era, however, the word has presently been changed so that it may also be used as a verb (Shituraeru) to express an action to decorate inside of the rooms for hospitality to visitors). That is to say, being different from a simple interior coordination, Shitsurai has been transmitted as an interior design using natural materials for expressing hospitality to visitors.