Hi,
This is very likely to be the chop of the publisher of the book, showing the copyright ownership.
Japanese books used to have colophon at the very end of the book. This is called "Oku-zu-ke", and the copyright was controlled by either directly applying the chop to that page or sticking a small piece of paper with the chop of the copyright owner.
Here is an example of such usage from my bookshelf; a textbook on mathematics (elementary number theory) by Dr. Teiji Takagi, a world renowned mathematician, with a chop "Taka-Gi" on a piece of paper, with inscriptions mentioning "Copyright Owner" on the top and the name of the publisher, Kyoritsu Shuppan Co., Ltd., at the bottom.


It is often very hard to decipher the characters on chops because they often use deformed fonts. As for the one shown by Mikeystamp, I guess the first character is "Nichi, the last is "Doh", and the middle is a mystery...
- Hironobu