retchōsō 列帖装

Also tetsuyōsō 綴葉装 or retsuyōsō 列葉装.
A multisection book. A type of Japanese book-binding. The first three to five sheets of paper are piled up and folded in half to make a set. Then several sets of folded sheets are arranged in a neat pile with the folded edges forming the spine. The binding is made by sewing the sections together using a complex and time-consuming procedure. The finished book, therefore, can be opened perfectly flat.
Retchōsō originated in Japan in the 12th century, and was widely used for works of native literature, including narrative stories *Noh 能 texts, and anthologies of Japanese poetry waka 和歌. It was not used for Chinese or Buddhist texts. Confusingly, the terms *kochōsō 胡蝶装 (butterfly book) and *yamatotoji 大和綴 are sometimes used to refer to multisection books, and during the late Edo period even the term *detchōsō 粘葉装 became confused with retchōsō.