Skip to 0 minutes and 3 secondsNext, I will explain the fukurotoji or "pouch" binding method. Just as with the detchōsō and tetsuyōsō methods, the leaves are folded in half before binding them, but the positioning of the fold is different. In fukurotoji books the fold comes on the outer side of the book and it is the loose side of the pages that gets bound, so the paper, as you can see, looks a bit like a pipe or tube, which means that only one side of the leaf, the front side, is used. Because there is no need for thick paper that can be used on both sides, most books were made using the thinner kōzo (choshi) paper.

Skip to 0 minutes and 55 secondsFirst, the leaves are folded, then they are stacked up and fastened with simple paper strings called koyori. If the book was intended for study or home use, the title would often be written directly here and the book would be left without a cover. Such books still belong to the fukurotoji category, but as they are only partially bound, they are known as karitojibon (half or partially-bound books). There are two ways to make a karitoji. The most common is to punch two holes through the stacked leaves, pass the strips through each of them, and then fasten them as in this example here.

Skip to 1 minute and 45 secondsIn this example here, I think you can these three small circles here, you pass the strips through each hole, leave a bit more than the thickness of the book, then you work the part that sticks out with your fingers, and finally you flatten it in with a wooden mallet until it resembles the head of a metal nail. You repeat the process on both sides. This is called shiteisō ("paper-nail" binding). It was particularly common in fukurotoji books dating from pre-Muromachi, pre-16th century times. Sometimes the binding was removed when the book was disbound for repairs, but generally speaking the shiteisō tends to be used in older books so it merits special attention.

Skip to 2 minutes and 48 secondsThe problem is that when the book has a cover, as in this case, it is not so easy to tell whether it was bound using the karitoji or shiteisō method. So what you do is run two fingers here along the thread and feel the part that bulges out to see if it is round or long and narrow, and from that you can sometimes tell how it was bound. Edo-period printed books―the item you see is a printed book― were usually bound using the fukurotoji method. Because of it popularity, a huge number of them was produced, so much so that when people today think of traditional Japanese books the image they tend to picture is that of a fukurotoji book.

Skip to 3 minutes and 47 secondsThat’s just how popular the method was. It is not easy to say when the method first started to be used, but if we look at very early examples, they tend to have writing on both sides of the paper. We noted earlier that fukurotoji books only have text on one side. Because paper was so valuable in early times, it was not discarded after one use but was kept to be reused. For instance, people might keep the letters they received, turn them over, and use the available side to make a fukurotoji to make a personal copy of a book. In this book, the thread has now come off, but originally it was bound as a fukurotoji.

Skip to 4 minutes and 38 secondsThis book is in fact a rather interesting case. It has writing on the reverse, and that writing is a Buddhist sutra. Originally a scroll, it was cut into segments, which were then turned over and used to make a fukurotoji book. It is an extremely rare example. Sometimes fukurotoji books can have such rare histories, so it is important to be aware of it. Next, perhaps it is not entirely accurate to discuss these alongside fukurotoji books, but their appearance, the fact that they are bound with thread, they look like fukurotoji books. But as you turn the pages you realize that there is a fold at the bottom of every page, as in the origami tetsuyōsō.

Skip to 5 minutes and 40 secondsThey have the crease here at the bottom, were cut along this side, bound using the karitoji method, and then the cover was added. Such books are called nagachōtoji ("wide" binding). You occasionally come across handwritten books bound using this type of binding, but printed books in this format, including the one I am looking at now, tend to be by the Kyoto bookseller Hachimonjiya. That’s it for pouch binding.

Main Binding Methods 5 - Fukurotoji

Read the article then watch Prof. Sasaki introduce the pouch binding method.

V. Fukurotoji (“bound-pocket” or “pouch” binding)

*Fukurotoji* (“bound-pocket” or “pouch” binding)
Fig.1 Above: Pouch binding (Unit: * Satsu*)

By far the most popular method in terms of number of books produced is the fukurotoji (variously translated as “bound-pocket,” “stitched,” or “pouch” binding). It was commonly used in China and Korea for printed books, and was known in China as xianzhuang (J. sensō). The sheets are folded “mountain fold” in two, placed on top of each other, and fastened using koyori paper strips. Covers are then added and everything is bound together with thread. (See below)

Itsukushima mōde-ki Fig.2 Example of Fukurotoji: Heike Monogatari.
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Only one side of the paper was used, so it is usually very thin. Early books bound using this method were often made with pre-used paper (such as letters), by writing on the “clean” side.(See below)

Chōrokubumi Fig.3 Example of Fukurotoji: Chōrokubumi.
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The oldest examples date from the 13th century, but it came into widespread use from the 15th century onward as a simpler alternative to the tetsuyōsō method. With the rise of commercial publishing in the 17th century, its popularity increased further, and its use now extended to handwritten books as well. Books bound in this style but without a cover are called Karitojibon (“semi-bound” books). (See below)

2 books (Left) Fig.4 Example of Fukurotoji: Rikutō Click to take a closer look
(Right) Fig.5 Example of Fukurotoji: Hekianshō Click to take a closer look

A relatively rare variant of the fukurotoji method with the fold at the bottom of the page and the binding on the right-hand side is called nagachō-toji (wide-page binding). (See Below)

Keisei kintanki Fig.6 Example of Fukurotoji: Keisei kintanki.
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Books bound in the fukurotoji style are counted in satsu (volumes). Some scholars also count tetsuyōsō and detchōsō-style books in “volumes,” but as this can potentially lead to confusion with fukurotoji books, the term jyō is preferable for the former.

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Japanese Culture Through Rare Books

Keio University