Most people will have never heard of Mr Maki Kaji, but if you are one of the millions around the world addicted to the number logic game Sudoku, you owe him a small debt of gratitude.
In 1984, he found a variant of the game in an American puzzle compendium, sans the name it is now best known by. The mind-stumper had existed for more than a century in Europe and the United States, in different forms.
Mr Kaji, now 62, tested it on the readers of his own puzzle quarterly Nikoli and after some polishing, he launched it in his home country of Japan.
After a time, he give it its now famous name, a contraction of the Japanese phrase for "the digits must be single".
Mr Wayne Gould, a New Zealand-born judge based in Hong Kong, discovered the brain-teaser in a Japanese bookshop and sold the concept to The Times newspaper in London in 1997. It sparked a craze in Europe and then around the world, helped in part by the unifying brand name created by Mr Kaji.
Now in Singapore as part of a tour to promote the game in schools and other associations, the Godfather of Sudoku, as his promotional material states, tells Life! about how his role today as president of Nikoli is being an ambassador for the puzzle, which he hopes to promote to newspapers and magazines as reader entertainment.
His Tokyo-based publishing house has 23 members of staff, largely in editorial, and mostly involved in puzzle creation, either crafting new editions or testing ones submitted by readers. The company is also a supplier of Sudoku puzzles to newspapers, 150 in Japan and 18 around the world.
In Japanese and halting English, he explains why Nikoli retains human puzzle crafters, whose names are printed next to the grid squares.
While it is easy and cheap to create computer software that generates valid Sudoku games, machine-made grids tend to be chaotic, lacking the symmetry of structure that fans find so satisfying.