Two Japanese boxers have died from brain injuries sustained in separate bouts on the same card at Tokyo?s Korakuen Hall.

Shigetoshi Kotari, 28, collapsed shortly after completing a 12-round draw against Oriental and Pacific Boxing Federation junior lightweight champion Yamato Hata on Aug. 2.

He underwent emergency brain surgery for a subdural hematoma ? a condition where blood collects between the brain and skull ? but died on Friday.

?Rest in peace, Shigetoshi Kotari,? the World Boxing Organization wrote on social media. ?The boxing world mourns the tragic passing of Japanese fighter Shigetoshi Kotari, who succumbed to injuries sustained during his August 2nd title fight.

?A warrior in the ring. A fighter in spirit. Gone too soon. Our thoughts and prayers are with his family, team, and the entire Japanese boxing community.?

On Saturday, fellow 28-year-old Hiromasa Urakawa died after suffering the same injury during a knockout loss to Yoji Saito. He had undergone a craniotomy in an attempt to save his life.

?This heartbreaking news comes just days after the passing of Shigetoshi Kotari, who died from injuries suffered in his fight on the same card,? the WBO said in another social media post on Saturday. ?We extend our deepest condolences to the families, friends, and the Japanese boxing community during this incredibly difficult time.?

In response, the Japanese Boxing Commission has announced all OPBF title bouts will now be reduced from 12 rounds to 10.

Earlier this year, Irish boxer John Cooney died a week after being taken into intensive care following his Celtic super-featherweight title defeat to Nathan Howells in Belfast. (CNN)

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