Kohei Uchimura of Japan competes in the horizontal bar during the Artistic Gymnastics NHK Trophy on May 16 in Nagano, Japan. Photo: VCG

He's the Japanese gymnastics superstar with a sweet tooth heading to his fourth Olympics, but this summer promises to be a different experience for "King" Kohei Uchimura.

The 32-year-old etched his name into Olympic history at the Rio Games in 2016, becoming the first male gymnast in 44 years to retain his all-around title.

He also led Japan to team gold in Brazil, cementing his place as one of his country's most revered athletes.

His chocolate-loving, Pokemon Go-playing persona has also made him a favorite with Japanese fans, revealing a different side to the man considered one of the best gymnasts ever.

But persistent shoulder pain has forced Uchimura to adjust his sights on home turf at the Tokyo Olympics, which will certainly be his last.

The gymnast, who took up the sport at the age of three, will forgo the defense of his all-around title to compete only on the horizontal bar.

His desire to win more Olympic gold remains as strong as ever though, and his rivals can expect nothing less than laser focus.

"If I had given a perfect performance here, it would have been difficult to top that at the Olympics," he said after qualifying for the Games at the All Japan Apparatus Championships in June.

"It's better to have made some mistakes, to make you more determined to train for the Olympics."

Uchimura took up the sport as a toddler in his native Nagasaki at the encouragement of his parents - both former gymnasts.

His iron determination and superhuman concentration soon brought him international success, and he won the first of his 10 world championship golds in 2009.

But he also cuts a relaxed figure away from the mat, making headlines at the start of the Rio Games after racking up a 500,000 yen ($4,500) phone bill playing Pokemon Go on his arrival in Brazil.

'Rock bottom'

His aversion to ­vegetables and fondness for "Black Thunder" chocolate bars are also well known, but when it comes to competition, he is all business.

"I just want to give a performance that I'm satisfied with," he said in June. 

"After that, it's up to the people watching to decide what they think."

Uchimura has struggled with injuries since the Rio Games, and had described his chances of appearing in Tokyo as "a fairytale" in 2019.

But after taking radical action and dropping every event but the horizontal bar, he is now ready to make his dreams come true.

"If it hadn't been for that, I don't think I would be here today," he said of his injury struggles. "I think people can come back stronger when they hit rock bottom."

Japan will have to do without him as they try to defend their team title in Tokyo. Uchimura recently described himself as "an ancient fossil" compared to newcomers such as 18-year-old Takeru Kitazono - winner of five gold medals at the 2018 Youth Olympics.

After his last Olympics, Uchimura is likely to stick around for one final world championship in Japan in October.