Kosei Tanaka Raced Through Four Divisions
Kosei Tanaka became a four-division world champion on February 24, 2024, defeating Christian Bacasegua by unanimous decision for the vacant WBO junior bantamweight title. The Japanese boxer reached that milestone in just twenty-one professional bouts.
Career highlights
Tanaka’s first world championship arrived in only his fifth professional contest in 2015. At nineteen, he outpointed Julián Yedras over twelve rounds in Komaki, Japan, for the vacant WBO minimumweight belt. His speed, combinations and movement helped secure a unanimous decision.
He subsequently won WBO championships at junior flyweight and flyweight before the victory over Bacasegua at 115 pounds. The WBO recognized him as the first male boxer to win its world titles in four different weight divisions.
The final professional chapter
Phumelela Cafu defeated Tanaka in October 2024 in what became his final fight. Tanaka announced his retirement in June 2025, aged twenty-nine, citing repeated eye injuries. He finished with twenty victories and two defeats, leaving a championship résumé distinguished by how quickly he climbed through the weight classes.
Tanaka’s early development included four national high school championships and an amateur record of forty-six wins and five losses. His father, Hitoshi, coached him, while former world champion Kiyoshi Hatanaka guided his professional career. Against Yedras, two judges scored the contest 117–111 and the third returned 115–113, all for Tanaka.
Sources
- World Boxing Organization: Tanaka’s first world-title victory
- World Boxing Organization: Tanaka’s fourth-division championship
- Reuters: Tanaka announces retirement after repeated eye injuries
