It's a beautiful book, interesting and lovely. I enjoy mathematical problems and I enjoy studying Japanese culture. This book satisfies both my interests! There is just one minor thing that's missing - the Japanese names are written entirely in Romanji. When I first started reading the book I kept wondering what is "sangaku" in Kanji. Most of my Japanese friends have not even heard of it. After much searching, I discovered the kanji for sangaku is ZZŠz, or mathematics tablets. The same romanji, "sangaku", could also have been these two kanji, ZZŠw, study of mathematics. I hope the next edition of this book would include kanjis or at list an index of the kanji, it makes life easier for students of Japanese. Bottom line is, this is an excellent book, and anyone interested in Japanese culture would be interested in this book.