Who would've thought that a book with Sudoku variant puzzles of such a high difficulty would be published in 4 Volumes? Yet, here it is. Volume 4 of a highly successful Killer Samurai series of books contains 75 of the most challenging Sudoku variation puzzles - Killer Samurai, split evenly into three difficulty levels: easy, medium and hard. In addition, this time you also get 25 Jigsaw Samurai Sudoku puzzles as a gift. All in all, there are 100 NEW puzzles in Gattai-5 format. These puzzles come from Djape, the author of Sunday's Samurai Sudoku for The Washington Post