Ryuya Yamanaka retained his strawweight world title in his first defense as he made challenger Moises Calleros quit on his stool after the eighth round on Sunday at the Portopia Hotel in Kobe, Japan.
Yamanaka (16-2, 5 KOs), 22, who was fighting in his hometown, doled out a beating to Calleros (28-8-1, 16 KOs), 28, of Mexico, before he retired after the eighth round. Yamanaka, who won his ninth fight in a row, was ahead on all three scorecards after eight rounds 80-72, 80-72 and 78-74.
In another fight on the card, Carlos Canizales (20-0-1, 16 KOs) won a unanimous decision over Japan's Reiya Konishi (15-1, 5 KOs) to win a vacant secondary junior flyweight world title.
Canizales, 25, of Venezuela, dropped Konishi, 24, who was fighting in his hometown, in the third round but had to overcome intense pressure from the challenger to claim the belt on scores of 116-111, 115-112 and 114-113.
Konishi, who was moving up in weight from the strawweight division, attacked Canizales with body punches that slowed him down, but Canizales caught a second wind and closed strongly to win the highly competitive fight.