Sohei Sudoku are a partial overlapping arrangement of four standard Sudokus. It has four merged grids. Each grid has two overlapping areas This Sohei Sudoku book is packed with the following features: - 400 easy to hard Sudoku puzzles overlapping into 100 Sohei Sudoku style - Answers to every puzzle are provided. - Each puzzle is guaranteed to have only one solution. Includes free bonus puzzles you can download book (Tons of Sudoku Puzzles for Adults & Seniors) Includes free bonus puzzles you can download book (Word Search With Hidden Message: 102 Puzzles for Adults and Seniors)