A Thirteenth Century Buddhist Manuscript
It is bound in the pasted-paper leaf (detchōsō) format in which each leaf of paper is folded in half and bound to the next leaf using glue at the fold. Every second two-page spread cannot be opened completely as the glue leaves a thick, stuck-together portion in the middle. We can see damage to the pages and particularly the spine of the book, where the pages are glued together, from insects who feed on the glue. Although this format was not widely used after the thirteenth century (with binding formats using thread rather than glue being favored for their durability), it remained in use among the Shingon sect of Buddhism, which is related to the fact that founder of Shingon, Kūkai, brought important books bound in this style back from China. As a Shingon text then, Kongōkai nenju shidai is a good example of the pasted-paper leaf binding format.