Koshido (lattice door) (格子戸)

Koshido or lattice door can be either a sliding or swinging door style.

Koshi (格子)' is often written as '隔子' in old documents; there is a description in a document, Kawachi-no-kuni, Kanshin-ji, Engi Shizaicho (Official Register and Inventory for Kanshin-ji Temple, Kawachi Province) that in 884, in front of the Nyohodo four pieces of 'koshido (隔子戸)' were being built.

The use of the letter "do (or to 戸)" implies that they were Chinese continental style swinging doors rather than shitomi (a generic term for timber shutters or doors that generally have vertical and horizontal lattice attached to the exterior surface and sometimes to the interior surface as well).

Swinging door type koshido became more common for the front side in temple architecture; further, according to "Tonomine Ryakki" (brief sketch of Tonomine), narabido (two temples) style Kodo (lecture hall), which was built in 972, had a 5-ken (about 9 m) width koshido at the front of naijin (inner sanctuary of the hall), and three units of koshido to divide naijin and gejin, or the inner sanctuary and the adjacent area.

In late Heian period, the sliding style became widespread.

In "Genji monogatari emaki" (the Illustrated Handscroll of the Tale of Genji), and "Nenchu-gyoji Emaki" (illustrated handscroll of annual events), depicted black lacquered koshido, being used as sliding doors or built-in dividers.

In Hoo-do Hall of Byodoin Temple, which was built by FUJIWARA no Yorimichi in 1053, there is a door on the opening areas of the peripheral wall, and koshi-yarido (latticed sliding door) was also used on the inner side.

In this way, koshi-yarido allows utilizing outside natural light and air effectively while functioning as a divider. Based on the function, it can be considered as a predecessor of akari-shoji (a translucent screen or sliding door made by pasting single sheets of white Japanese paper on light wooden frames).