A sushi chef in Japan is continuing in his job, even though he just became 100. His name is Jiro Ono. He celebrated his 100th birthday this week. He is one of 4,380 people in Tokyo who have become or will be 100 this year. Mr Ono spoke to Tokyo governor Yuriko Koike. She asked him about his secret to a long and healthy life. He replied, "To work." He said: "Even at 100 years old, I'll try to work if possible. I believe the best medicine is to work." He told Ms Koike: "I plan to keep going for about five more years." Ono said he has no plans to retire from his job.

Jiro Ono was born in 1925. He started working when he was seven. Eighteen years later, he moved to Tokyo. He worked in a sushi bar. He qualified as a sushi chef in 1951 and opened his own restaurant in 1965. It was a tiny 10-seat place in a rich area of Tokyo called Ginza. He spent many years trying to make the perfect sushi. He was rewarded when he received three stars in the Michelin Guide. In 2011, a movie was made about him called "Jiro Dreams of Sushi". In the film, he said: "I haven't reached perfection yet. I'll continue to climb and try to reach the top."