Japan's Kosei Tanaka poses for photographs in July 2024. Photo: AFP
The Japanese fighter is the fastest boxer to earn belts at four different weights, winning the WBO strawweight, light-flyweight, flyweight and super-flyweight titles in 21 fights, surpassing American Oscar De La Hoya's record of 24 fights.
Having made his professional debut at 18, Tanaka retires with a record of 20-2. His last fight was in October when he lost to South Africa's Phumelele Cafu.
He said he underwent surgery on both eyes after the bout.
"I'm retiring as a professional boxer. 11 years of professional life ... The reason is all about my repeated eye injuries...," Tanaka posted on social media.
"Due to the effects of hernia operations on my neck and many, many operations on my eyes alone in the four years from 2021, my eyes have become brittle and I can no longer spar, let alone compete.
"I decided to retire because there was no way for me to get into the ring."
- Reuters
