Sudoku is a logic-based, combinatorial number-placement puzzle. In classic Sudoku, the objective is to fill a 9 × 9 grid with digits so that each column, each row, and each of the nine 3 × 3 subgrids that compose the grid contains all of the digits from 1 to 9. The puzzle setter provides a partially completed grid, which for a well-posed puzzle has a single solution.

Japanese is the principal language of the Japonic language family spoken by the Japanese people. It has around 120 million speakers, primarily in Japan, the only country where it is the national language, and within the Japanese diaspora worldwide.