He also surpassed Oscar De La Hoya to become the fastest four division champion, setting the bar at 21 fights.

In November 2014, Tanaka defeated previously unbeaten Ryuji Hara via tenth-round technical knockout (TKO) to win the OPBF mini-flyweight title.

[4] 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.

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.

[13] 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.

[16] Tanaka faced 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.

In the eighth round, Ioka caught his opponent with another hard counter left hook, and referee Michiaki Someya caught Tanaka before he could fall and waved off the fight, with Ioka inflicting Tanaka with his first professional loss and retaining his WBO title via eighth-round technical knockout.

[18] Tanaka was booked to face the one-time WBA super-flyweight title challenger Sho Ishida on 11 December 2021, at the International Conference Hall in Nagoya, Japan.

[20] Tanaka faced the reigning OPBF and WBO Asia Pacific super flyweight champion Masayoshi Hashizume, for the latter title, at the Korakuen Hall in Tokyo, Japan on 29 June 2022.

[26] Tanaka was originally scheduled to make the first defense of his WBO super flyweight title against Jonathan Rodriguez at Ryōgoku Kokugikan in Tokyo, Japan on July 20, 2024.

[31] He is the cousin of Japanese figure skater Yuhana Yokoi and younger brother of amateur fighter Ryomei Tanaka.