I sourced it from the flygo website, where there are solutions.
I've not included the solutions here as they may be copyrighted.

May all old out of print books suffer the same fate.

So why flag up a copyright-infringing site?

EDIT: Cassandra, added text to a solution can easily alter what you describe.

IIRC, literary work by Germans is protected 70 years after the last publication according to the (possibly inherited) copyright. I do not know about periods under Japanese law.

Works authored by an individual, under their own name or a known pseudonym, are protected for fifty years following the individual's death. Works authored anonymously or under an unknown pseudonym, as well as works authored by corporations, where the individual author or authors are unknown, are protected for fifty years following publication. As of May 2014, in the ongoing Trans-Pacific Partnership negotiations, Japan had reportedly agreed to extend the duration of protection to seventy years to be more in line with the United States and other nations.[7]

Cinematographic works are protected for seventy years following publication (or seventy years following creation, if the work is not published).[8] This update was made in 2004 to be more consistent with other nations around the world, as the previous term was fifty years. However, in 2006 the Tokyo District Court said that the 2004 law cannot be applied retroactively, so that all cinematographic works published (or created, if not published) before 1953 are now public domain.[9] However, in 2007 the Tokyo District Court ruled that for works (in particular from Akira Kurosawa) released before and in 1970 copyright protection is extended until 38 years after the original copyright holder's death.[10][11]

Neighboring rights apply for fifty years after the work is performed, transmitted, or put on sale.

Works authored by, or transferred to, residents of countries which were Allied Powers in World War II, before the effectuation of the San Francisco Peace Treaty, are given some prolonged protection by an exemption law. This extension compensates for the unprotected period in World War II, and varies with the country of the author or the copyright holder in the wartime. The prolongation is normally by 3,794 days (including Australia, Canada, France, United Kingdom, and the United States), but some countries ratified later, and have longer wartime (the longest is 4,413 days for Lebanon).

One other thing that struck me when I looked up information about the book, is that Segoe died before I was born. So we're talking about a book which has long been out of print, by an author who died a long time ago. To me, this would easily make this book as much of a piece of classical literature as Gokyo Shumyo. Especially since we're still talking about it so many years later.

From http://en.wikipedia.org/wiki/Copyright_law_of_Japan
Length of protection

...
Being out of print is not a valid reason for copyright infringement.
...

I have strong mixed feelings about this. I love purchasing go books, not only because I like them but also as encouragement for writers. But I'll take as example a book I own and IIRC you know something about: How to Improve on a 5x5 board, by Fukui Masaaki. How could I, on the west, legally (actually there's even no way to do it illegally) get this book?

I was curious if I could find one right off the bat but failed. Six copies are on amazon.co.jp but limited to Japan only shipping. Akashiya would be a best bet since they will ship internationally and may have it. Nowadays, it's not too hard to find the books and get them shipped out.

edit...
Actually I was looking at this.
http://www.amazon.co.jp/s/ref=nb_sb_nos ... 2%E7%A2%81

This one you can just buy new and have it shipped anywhere.
http://www.amazon.co.jp/%E7%94%BB%E6%9C ... 2%E7%A2%81

Edit: also, there's a matter of convenience. A year or so ago I read a submission on HackerNews about why people pirated Game of Thrones, and the usual answer was not because it was cheaper, no. A lot of "pirates" were actually paying for HBO go or whatever it is called to watch it on their computers/devices through the producer. But it worked *so* bad and rarely that for them it was much more convenient to get it illegally.

We tend to have both here. People who like the pdfs of Cho Chikun's Encyclopedia of Life and Death and people who just would never pay anything getting it for free. This pdf is a continuation of that trend.