Yamanaka retains belt with fifth straight KO
Champion Shinsuke Yamanaka of Japan (L) sends Belgium's Stephane Jamoye to the canvas during the WBC bantamweight title match in Osaka on April 23, 2014
Panamanian referee Hector Afu stopped the fight 11 seconds into the ninth round when southpaw Yamanaka's straight left to the body sent Jamoye to the canvas.
It was Yamanaka's sixth defence of the 53.5-kilogramme-class title which he won by beating Mexico's Christian Esquivel with a technical knockout in Tokyo in November 2011.
His unscathed professional record improved to 21 wins, 16 of them inside the distance, and two draws. He has triumphed in five title bouts in a row by a knockout or technical knockout.
It was the fifth loss for European bantamweight champion Jamoye, the number-three WBC contender, who has 25 wins to his name, 15 of them by knockout.
"It was great that I could finish the fight with a knockout," said Yamanaka, 31. "I relied too much on my left hand to throw combinations."
"I want to fight abroad and fight in a bout to unify world titles (from different organisations)."
Right-handed Jamoye, 24, said Yamanaka's punches were "very strong".
"I knew it would be a tough fight. I am still young and I will think about (another world challenge) after developing my skills further," the Belgian said.
Yamanaka dominated throughout against Jamoye, who was seeking to become the first Belgian world boxing champion in his first shot at a world title.
Yamanaka's first knockdown of the night came in the second round when his straight left caught the Belgian's face.
In the eighth round, the champion floored Jamoye with a straight left to the body and again with a blow to the face.
The Belgian managed to tough it out but the end finally came only seconds into the ninth round when Yamanaka's left body blow sent Jamoye down for the fourth time at the Osaka Castle Hall in the western city.