Junto Nakatani stopped Vincent Astrolabio from the Philippines in the first round at the Kokugikan in Tokyo, Japan, on Saturday.
As a result of if the win, the 26-year-old Japanese boxer retained his World Boxing Council (WBC) bantamweight title after a straight left sent Astrolabio to the canvas.
Nakatani improved his record to 28 wins with 21 knockouts while the 27-year-old Astrolabio dropped to 19 victories (14 stoppages) and five defeats.
Meanwhile, unbeaten Japanese boxer Tenshin Nasukawa stretched his unbeaten run to four wins after he stopped Puerto Rico-born American Jonathan Rodriguez in the third round.
