Millions have succumbed to the phenomenon of Suduko, and it has spawned thousands of books, websites and daily puzzles in a number of national newspapers throughout the world. Yet in Japan, home of Sudoku, Kakro, or Kakuro is a far bigger phenomenon, appearing in over 70 different magazines and newspapers with over one million Kakuro books sold to date.

While Sudoku uses a straightforward grid, a Kakuro consists of filled and empty cells similar to a crossword puzzle. Some black cells contain a diagonal slash with numbers in them, the clues, creating exciting, addictive puzzles that will allow the growing army of Sudoku fans to stay one step ahead of the game.