By Boxing Insider Staff

Naoya Inoue defends the undisputed super bantamweight title against Junto Nakatani on May 2 inside a sold-out Tokyo Dome. He will walk to the ring 32-0, with 27 knockouts, holding belts in his fourth weight class, ranked No. 2 pound-for-pound in the world. He is one of three men in boxing history to be undisputed champion in two divisions during the four-belt era, alongside Terence Crawford and Oleksandr Usyk.

For American fans who have only caught Inoue in glimpses, against Fulton, against Tapales, on the Riyadh cards, here is the longer story.

Zama, Kanagawa

Inoue was born April 10, 1993 in Zama, a small city in Kanagawa Prefecture, southwest of Tokyo. His father Shingo, a former amateur boxer who had stepped away from the sport to run a painting company and support his family, put gloves on Naoya at age five. Shingo never left the corner. He still trains his son today, and was at his side through every round of camp for the Nakatani fight.

The Inoue household produced two professional fighters. Naoya’s younger brother Takuma, born in 1995, will fight on the May 2 undercard, defending the WBC bantamweight title against four-division champion Kazuto Ioka. Their cousin Koki Inoue turned professional in 2015 and competes at super lightweight.

Amateur Years

Inoue announced himself in 2009, winning the Japanese Interscholastic Athletic Meeting and the Japanese Junior National Championships in the same year. He took bronze at the 2010 Asian Youth Championships in Tehran and gold at the 2011 President’s Cup in Jakarta. He reached the round of 16 at the 2011 World Amateur Boxing Championships in Baku and lost in the final of the 2012 Asian Olympic Qualifiers in Astana, missing out on the London Games.

He finished his amateur career with a record of 75-6, with 48 of those wins coming inside the distance, an unusual knockout rate for amateur boxing anywhere and remarkable for a Japanese amateur program that rarely produces medalists at senior international level. He turned pro in 2012 at age 19 rather than wait for another Olympic cycle.

Signing with Ohashi

Inoue signed with Ohashi Boxing Gym in Yokohama, the operation run by former WBC and WBA minimumweight champion Hideyuki Ohashi. The agreement included an unusual clause: Inoue committed in writing never to take an easy fight on his own initiative. He has held to it.

His professional debut came on October 2, 2012 at Korakuen Hall in Tokyo against Filipino national champion Crison Omayao. Inoue dropped him in the first round, dropped him again in the fourth, and stopped him at 2:04 of that round. The fight set a tone the rest of the career would not break.

The Climb

By his sixth professional fight he was a world champion. Inoue stopped Adrián Hernández in six rounds at Ota-City General Gymnasium in April 2014 to win the WBC light flyweight title. Hernández had gone 8-1 in world title fights before that night. Inoue made one defense, then moved up to junior bantamweight, where he beat Omar Andrés Narváez, a 43-1-2 veteran with 27 prior title-fight defenses, by second-round knockout in December 2014.

Seven defenses followed at 115 pounds before he moved up again. At bantamweight he stopped Jamie McDonnell in the first round in May 2018, then entered the World Boxing Super Series tournament. He knocked out Juan Carlos Payano in 70 seconds in the quarterfinal (Ring Magazine Knockout of the Year), stopped Emmanuel Rodríguez in two in the semifinal, and beat Nonito Donaire by unanimous decision in the November 2019 final to win the inaugural Muhammad Ali Trophy. The Donaire fight, in which Inoue suffered a fractured orbital bone in the second round and continued, was Ring Magazine’s Fight of the Year.

He stopped Donaire in two in the rematch in June 2022, then stopped Paul Butler in eleven in December 2022 to become the first undisputed bantamweight champion since Enrique Pinder in 1972 and the first ever in the four-belt era.

Becoming the Monster at 122

Inoue moved up to super bantamweight in 2023 and immediately took over the division. He stopped unified WBC and WBO champion Stephen Fulton in eight rounds at Ariake Arena in Tokyo in July 2023, then unified the four belts with a tenth-round knockout of WBA and IBF champion Marlon Tapales in December 2023, becoming the first undisputed champion at 122 pounds in history.

Six defenses have followed. He stopped Luis Nery, who had dropped him in the first round, in six in May 2024. He stopped Sam Goodman, T.J. Doheny, and Ye Joon Kim. He outpointed Murodjon Akhmadaliev over twelve in September 2025. He outpointed Alan Picasso over twelve at the Riyadh card on December 27, 2025, the same night Nakatani beat Sebastian Hernandez on the undercard. Nakatani will be the seventh defense.

The Style

Inoue is listed at 5-foot-5, an orthodox stance, with a knockout-to-win percentage of 84 percent across his pro career. He fights with a counterpuncher’s patience built around a finisher’s instinct. His jab sets distance. His feints, with shoulder and head, draw the response that opens up the right hand or the left hook to the body.

The body work is the signature. Picasso, Doheny, Dasmarinas, and others have ended fights folded around the ribs rather than flat on their backs. The power is what gets the highlight reel, but the body attack is what wears opponents down round after round before the finish arrives.

Where Things Stand

Inoue is 33 years old, married since 2015 with three children, and lives in Yokohama within walking distance of the gym he has trained out of his entire pro career. He is the first Japanese fighter ever to top The Ring’s pound-for-pound list, a position he held in 2023, and currently sits at No. 2. ESPN has the Nakatani bout listed as the headline card of the May 2 fight calendar.

He has called Nakatani the toughest test of his career to date. “I definitely feel that he has grown rapidly recently,” Inoue said in a recent interview, “and with the new fights he has been having at the pound-for-pound level, I have a lot of respect for him and rate him highly.”

Inoue has indicated he plans two more fights at 122 pounds, including Nakatani, before moving up to featherweight. Matchroom CEO Eddie Hearn told reporters last weekend that preliminary talks have begun with Turki Alalshikh about a fight between Inoue and unified super flyweight champion Jesse “Bam” Rodriguez. Hearn said the bout is “inevitable” and could happen within Rodriguez’s next two or three fights.

That conversation is for after May 2. Before any of it can happen, the Monster has to walk through Junto Nakatani.