Top-ranked International Boxing Federation atomweight Sumire Yamanaka of Shinsei Boxing Gym hammered out a unanimous decision over Mika Iwakawa of Himeji Kinoshita Boxing Gym in a hard-fought bout and wrested the title at Tokyo’s Korakuen Hall on Jan. 12.

  After the 10-round fight, all three judges scored the fight in favor of the 22-year-old Yamanaka by a margin of two to eight points. Iwakawa, 40, failed in her first defense of the title she captured in September 2022.

  With the win, Yamanaka became Japan’s first brother-sister world champion as her stablemate and former World Boxing Organization minimumweight champion Ryuya Yamanaka is her elder brother.

  While there were no knockdowns, the left-handed Yamanaka got inside and landed right hooks and straight lefts to the head and body to pile up points from the opening bell.

  While the rangy Iwakawa occasionally connected with straight rights while moving side to side, Yamanaka continued to land the right-left combination punches throughout the fight.

  The undefeated Yamanaka now has an eight straight wins, three by knockouts, while Iwakawa fell to a 12-7-1 win-loss record with four KOs.