Though Japan has produced world-class boxers such as Naoya Inoue and Junto Nakatani, one of its highest medal-winning fighters, Kosei Tanaka, has formally retired from professional boxing.

The 29-year-old champion broke the news on June 4 through Instagram, pointing to long-term eye injuries as the motive for leaving professional boxing.

Eye Injuries Force Kosei Tanaka to Retire from Boxing

Former 4-Division Champion Hangs His Gloves at 29 Former 4-Division Champion Hangs His Gloves at 29
PHILIP FONG/AFP via Getty Images

In an emotional Instagram post, Tanaka announced his decision to retire due to serious eye problems. He stated that he battled his last fight on October 14, 2024, with vision already impaired and had recently undergone surgery on both eyes right after the fight.


"Although my vision has recovered, my vision in my right eye is still significantly distorted, and I can't focus with both eyes. Due to the effects of hernia surgeries on my neck and many, many surgeries on my eyes alone in the four years from 2021, my eyes became brittle, and I was unable to spar, let alone compete. I decided to retire because there was no way for me to get into the ring," Tanaka said in Japanese (translated to English).

A Distinguished Career: Four Divisions, Lightning Speed Titles

Tanaka's retirement is surprising to all his fans, given his age. He's one of the most promising boxers in Japan. He is a four-division world champion, having won:

  • WBO Mini-Flyweight Title (2015–2016)
  • WBO Junior-Flyweight Title (2016–2017)
  • WBO Flyweight Title (2018–2020)
  • WBO Junior-Bantamweight Title (2024)

According to Sports Illustrated, he made history by becoming the quickest Japanese fighter to achieve a world title, claiming his first belt in just his fifth professional fight way back in 2014. That was the starting point of one of Japan's greatest boxing careers.

Tanaka's Legacy Will Be Forever Remembered

Tanaka finishes his professional career with a record of 20 wins, 2 losses, and 11 knockouts. Although he ended his career on a low note after losing to Phumelela Cafu, it's still an impressive feat to have this smooth record.

Although he retired at a fairly young age, Tanaka's achievements say it all. At a time when Japanese boxing has earned the world's respect, his name is among the nation's greatest of all time.