This isn't a book you read (well, OK, I read it, but this is an area of intense interest to me as an Asian art specialist) but rather you want to have as a reference guide (actually, it's a bit like my own reference to Chinese Art--Chinese Art: A Guide to Motifs and Visual Imagery--you can read it in parts but it's not a cover-to-cover read).
It is, however, an excellent one-volume reference work to all the motifs, symbols, and stories you find used as netsuke motifs (the pendants or toggles that were used to support medicine boxes, tobacco pouches and similar objects suspended by a cord from a Japanese obi). These are highly collectible items that have reached top collector prices unfortunately, but they are wonderful repositories of some of the best-known and loved Japanese folk tales, mythology and historical events, enabling one to identify not only the most common netsuke but also some of the motifs found on Japanese lacquerware, ceramics, screens and other decorative art.
For true netsuke collectors, there is also an invaluable section showing all the names and dates of the most famous netsuke carvers with their names in English, Chinese characters, the materials they worked in (wood, ivory, etc.) and the dates in which their products are found. Jonas first published this work in 1928, and it was republished in 1960 by Tuttle (the publisher of my own book, actually), so this list has not been updated although there have been new generations of netsuke carvers.
This is a classic work; difficult to find but if you're interested in Japanese art and culture, a treasure trove.