In an interview a year ago, Watanabe said his secret to longevity is "not to get angry and keep a smile on your face".
The 112-year-old has led an incredible life, having been born in Niigata in 1907 as the oldest of eight children before going on to work in agriculture in Taiwan and eventually serving in the Pacific War in 1944.
He is now four years shy of being crowned the oldest man ever to live, a title which belongs to 116 years and 54 days old Jiroemon Kimura, also from Japan.
Watanabe was officially given the title at a nursing home in Niigata where he now resides.
A 112-year-old Japanese who has been recognized as the world's oldest living man cited "laughter" Wednesday as the secret to his longevity. Don't get angry and keep smiling.
After graduating from agricultural school he moved to Taiwan and worked on sugar cane plantation contracts and lived there for 18 years with his wife Mitsue and their children. According to Yoko Watanabe, wife of Mr Watanabe's first son, "getting to places and sourcing food was a struggle".
The world's oldest living person, Kane Tanaka, also lives in Japan. She lived to 122 years and 164 days before dying in August 1997.
For the next 38 years - until Chitetsu was 104 - they grew potatoes, tomatoes, strawberries and plums on the land together. "He's also caring. When I was working on my patchwork hobby, he was the one who praised my work the most", Yoka continued. "I think having lived with a big family under one roof, mingling with his grandchildren and great-grandchildren helped keep a smile on his face as well".
According to GWR, Tanaka, who was born on January 2, 1903, owned the title of the world's oldest living person and the world's oldest living woman in 2019.