I am selling this because I no longer read it. Please purchase only if you understand that this is a used item. This is a DVD book that compiles the popular "Pythagora Switch" "Pythagora Device" from NHK. In addition to 33 device videos, it also includes prototype videos from the laboratory. With the explanatory booklet, you can enjoy it while "decoding" the mechanism. - Title: Pythagora Device DVD Book 1 - Authors: Masahiko Sato, Masumi Uchino - Publisher: Shogakukan - Published: December 2006 - ISBN: 978-4-09-480311-2 - Price: 2,800 yen + tax