I saw that too and googled it without results.
Nice video - thank you for posting!
Found this:
His truely last original work, but not a book:
2009 Iroha Revolutionary Verses
いろは革命歌 (iroha kakumei uta);
Fukuoka, Masanobu's 47 hand-written classical song-verses (bilingual) and drawings, in pen and ink, also with photographs;
One large double–sided card for each of the 47 classical iroha–arrangement of Japanese syllables;
Includes a bilingual Fukuoka, Masanobu biography commentary booklet by Shōjaku, Mutsumi, having records of practically all his works, bibliography and main life accomplishments, together with the song verses cards;
(Japanese) bilingually with (English) translations – created with several translators, editors and contributors;
53p 15×10cm;
His testament and last creation;
Posthumously self-published in 2009 Feb 2, by 自然樹園 (小心舎) (Shizen Juen (Shou Shin Sha)) –one of his own self-publishing-publisher-names.
In print ISBN 978-4-938743-03-1.
In another article I found a second ISBN 4-938743-03-5
But an ISBN search shows they are both out of print.