was a Japanese businessman who was the president of Nikoli, a

puzzle A puzzle is a game, Problem solving, problem, or toy that tests a person's ingenuity or knowledge. In a puzzle, the solver is expected to put pieces together (Disentanglement puzzle, or take them apart) in a logical way, in order to arrive at th ...

manufacturer. He is widely known as "the father of

Sudoku Sudoku (; ja, 数独, sūdoku, digit-single; originally called Number Place) 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 ...

" for his role in popularizing the number game.

Early life

Kaji was born in

Sapporo ( ain, サッ・ポロ・ペッ, Satporopet, lit=Dry, Great River) is a city in Japan. It is the largest city north of Tokyo and the largest city on Hokkaido, the northernmost main island of the country. It ranks as the fifth most populous city ...

on 8 October 1951. His father worked as an engineer at a telecom company; his mother was employed by a kimono shop. Kaji attended Shakujii High School in his hometown. He later studied literature at

Keio University , mottoeng = The pen is mightier than the sword , type = Private research coeducational higher education institution , established = 1858 , founder = Yukichi Fukuzawa , endowmen ...

, but dropped out during his first year. After a succession of jobs including being a roadie, a waiter and a construction worker, he started a publishing business.

Career

Kaji launched a quarterly puzzle magazine in 1980 called ''Nikoli'', together with two friends from his childhood. They named the magazine after a

race horse Horse racing is an equestrian performance sport, typically involving two or more horses ridden by jockeys (or sometimes driven without riders) over a set distance for competition. It is one of the most ancient of all sports, as its basic pr ...

that had won the 1980 2000 Guineas Stakes race in Ireland. Three years later, he founded a company under the same name. The magazine, the company's main product, grew to have 50,000 quarterly readers. The number game

appeared in early issues of ''Nikoli''. His interest in the puzzle piqued after encountering it in 1984 under the title "Number Place". He formulated the name "Sudoku" while he was scrambling to get to a horse race. He shortened it from ''Suuji wa dokushin ni kagiru'' ("numbers should be single") at the urging of his fellow workers. After the game spread to Britain and the United States, it became wildly popular. Kaji also invented or introduced various other puzzle games, such as

Masyu is a type of logic puzzle designed and published by Nikoli (publisher), Nikoli. The purpose of its creation was to present a puzzle that uses no numbers or letters and yet retains depth and aesthetics. Rules ''Masyu'' is played on a rectangular ...

. He resigned as head of Nikoli on 31 July 2021, ten days before his death. He was succeeded as president by Nikoli's editor in chief, Yoshinao Anpuku.

Personal life

Kaji was married to Naomi until his death. Together, they had two children. Kaji died on 10 August 2021 at his home in

Tokyo Tokyo (; ja, 東京, , ), officially the Tokyo Metropolis ( ja, 東京都, label=none, ), is the capital and largest city of Japan. Formerly known as Edo, its metropolitan area () is the most populous in the world, with an estimated 37.468 ...

at age 69, from

bile duct cancer Cholangiocarcinoma, also known as bile duct cancer, is a type of cancer that forms in the bile ducts. Symptoms of cholangiocarcinoma may include abdominal pain, yellowish skin, weight loss, generalized itching, and fever. Light colored stool ...

. Nikoli's staff held a memorial gathering for him on 2 November in Tokyo.

References

External links

"Maki Kaji: First he gave us sudoku"
��'' Daily Independent'' (UK) newspaper article {{DEFAULTSORT:Kaji, Maki 1951 births 2021 deaths Deaths from cholangiocarcinoma Japanese businesspeople People from Sapporo Puzzle designers Deaths from cancer in Japan