Sho Kimura he is hoping to hold onto his WBO flyweight belt as long as possible after beating Chinese champion Zou Shiming last week.
The 28-year-old Kimura defeated Zou by technical knockout in Shanghai on July 28 in his first world title bout, stopping the 36-year-old two-time light flyweight Olympic gold medalist in the 11th round.
"It's heavy," Kimura said of the champion's belt he had with him at a news conference in Tokyo on Friday. "I want to be the champion for as long as I can."
Kimura became the first Japanese boxer in 36 years to win a world title outside Japan in a bout officially approved by the Japan Boxing Commission.
Kimura was stopped and asked to pose for photographs with Chinese people after his return to Japan and he said he was "delighted" with the response to his win.
He said he will bring the belt with him when he visits the grave of his mother Mayumi, who died after an illness when he was 20.
"I am grateful to her for bringing me into the world. I want to offer my thanks," he said.
