Challenger Katsushige Kawashima stopped champion Masamori Tokuyama on a technical first-round knockout to claim the WBC superflyweight title Monday.
Kawashima floored Tokuyama with a devastating right hook and the referee called a stop to the bout 1 minute, 47 seconds into the first round at Yokohama Arena.
Kawashima succeeded in the rematch after losing a decision to Tokuyama for the WBC title in June last year. Tokuyama failed in his ninth title defense.
"It seems like a dream and I still don't believe it," Kawashima said. "I didn't care if I won by decision or whatever. My body was moving very naturally."
A hard right sent Tokuyama to the canvas but the champion stood to continue on wobbly knees before Kawashima released another flurry to send him down for a second time.
Kawashima improved his record to 26 victories, including 18 knockouts, with three defeats while Tokuyama dropped to 30-3 (eight KOs) with one draw.
Earlier, Thai WBC minimumweight champion Eagle Kyowa won a 3-0 injury decision over challenger Satoshi Kogumazaka 2:24 into the eighth round to succeed in his first title defense. Kyowa improved to a spotless 13-0 with five KOs.