According to The Times of London, "Tetsuya Nishio is the undisputed grand 'puzzle master' of Sudoku: a bespectacled fiend from the darkest suburbs of Tokyo who spends his every waking hour devising abominable new ways to torture our brain cells. His only weapon is logic, but, in his own words, 'It is a knife that kills.' His commitment to deviousness is absolute."
Nishio is a world champion of number-logic puzzles. He reigns as the single-most important figure in Sudoku in Japan. He invented O'Ekaki (Paint by Sudoku) puzzles in the late 1980s, which are steadily becoming as popular as Sudoku. He is also the chairman of the Japan Puzzle Team at the annual World Puzzle Championships.
At the 2007 World Puzzle Championship, Nishio placed fourth amongst the greatest Sudoku puzzlers in the world!