A compilation of six books, bound in a single volume, on Ninjitsu. Dude looks like a metalwork teacher, but I guess to pack a powerful martial artist in an unassuming package is in keeping with principles of stealth. I can't speak for the contents in terms of granting the reader powerful abilities, but the book weighs about 1.6kg so you could probably drop someone if you threw the book hard enough. Bought this on a whim at a charity shop and noticed new copies on sale for £50 or so! Well this isn't a new copy, but there's some stuff I do want to buy, so I'm putting this up so someone who will appreciate it more doesn't have to pay quite as much as the going rate :)
eBay