I also got two nice books on Sangaku (算額) from Mr. Horibe.
The first one is a reprint of a famous Japanese math book (算法助術) originally published in the early 19th century.
A page from this book:
The second one is the catalog for an exhibition on Sangaku in Nagoya a few years ago (2005).
A page from this beautiful catalog:
Mr. Horibe said, however, very few people came to this exhibition.