Kosei Tanaka

Tanaka turned pro at the age of 18 in 2013. In November 2014, Tanaka defeated previously unbeaten Ryuji Hara via tenth-round technical knockout (TKO) to win the OPBF mini-flyweight title. In his next fight, Tanaka decisioned Julian Yedras (117–111, 117–111, 115–113) to win the WBO mini-flyweight title.[5] Tanaka holds the Japanese record for winning a world title in the fewest fights (five), surpassing the previous record held by Naoya Inoue of six fights.[6] Tanaka's only title defense at mini-flyweight came against Vic Saludar, whom he knocked out in round six after a left hook to the body. Saludar knocked down Tanaka in round six, and was ahead on all scorecards prior to the stoppage.[7]

In December 2016, Tanaka challenged former mini-flyweight title holder Moisés Fuentes for the WBO junior-flyweight title. Tanaka dominated Fuentes, dropping him in round five before referee Raul Caiz Jr stopped the fight, giving Tanaka a TKO victory. With the win, Tanaka became a two-weight world champion in just eight fights.[8] Tanaka's first defense came against prospect Ángel Acosta. The former won a wide unanimous decision (UD) (117–110, 117–110, 116–111) and dropped Acosta once. Acosta had won all 16 of his previous fights by knockout.[9]

Tanaka's second defense took place in September 2017 against little-known fighter Palangpol CP Freshmart. Tanaka was a huge favorite going into the fight, but Palangpol would prove to be Tanaka's toughest challenger so far, dropping the defending champion once in the first round and trading back-and-forth combinations for the rest of the bout. After a thrilling fight, Tanaka would finally gain the upper hand in round nine, as he knocked down Palangpol and continued to land big combinations as the challenger struggled to connect. Eventually, the referee stepped in and stopped the fight at 1:52 in round nine.[10][11][12]

Tanaka had previously sought a unification bout against WBA titleholder Ryoichi Taguchi in December,[13] but injuries during the fight against Palangpol would prevent him from fighting on that date.[14]

In December 2017, Tanaka vacated his junior-flyweight title to move to the flyweight division.[15] In September 2018, Tanaka defeated Sho Kimura to capture the WBO flyweight title, equalling Vasyl Lomachenko's record of becoming a three-weight world champion in just 12 fights.

In March 2019, Tanaka fought former WBA, IBF, lineal and The Ring junior flyweight champion and domestic rival Ryoichi Taguchi for the first defense of his WBO flyweight title in a one sided bout described as "action packed" by spectators. After the fight, Tanaka expressed regret that he did not deliver a knockout.[16]

In August 2019, Tanaka fought Jonathon Gonzalez after losing on all three judge's scorecards leading up to the seventh round, Tanaka delivered a brutal knock out to make a second successful defense of his WBO flyweight title.[17]

On New Year's Eve in 2019, Tanaka fought Wulan Tuolehazi, Tanaka delivered a brutal third round knockout after a one sided fight to defend his WBO flyweight title for the third time. Shortly after the bout, he vacated his WBO flyweight title, announcing that he intended to fight Kazuto Ioka for his WBO super flyweight title.[18]

Kosei Tanaka is scheduled to fight WBO super flyweight champion Kazuto Ioka on New Year's Eve 2020 in an attempt to win a major title in four divisions in the fewest fights. He will also become the second Japanese champion to win a major title in four divisions if he is victorious, the first being his opponent, Kazuto Ioka.[19]