Sudoku fever is on! Which book in the Martial Arts Sudoku series will provide the perfect challenge for you? The skill level recommended to solve these puzzles is ranked in the same way as Japanese karate levels—by different colored belts. Easy sudokus bore you, but The Black Belt collection never will. It’s the ultimate thrill for pros like you.

Sudoku fever is on! Which book in the Martial Arts Sudoku series will provide the perfect challenge for you? The skill level recommended to solve these puzzles is ranked in the same way as Japanese karate levels—by different colored belts. Easy sudokus bore you, but The Black Belt collection never will. It’s the ultimate thrill for pros like you.