The two went their own way, winning interim fights that have since set up the rematch that will take place on Sunday at Toyota Arena in Tokyo.

"He earned the right to become the challenger by winning the eliminator [against Juan Francisco Estrada]," Inoue (22-2, 5 KOs) told The Ring. "So my only task is to fight the top contender as a champion and become victorious again."

Inoue, who is rated No. 2 by The Ring at bantamweight, believes he saw improvement in him against Estrada.

"I got the impression that he has good eyes, like he can see what's coming and can react quickly," Inoue said. "I think he has gained more power.”

The 30-year-old, who decamped to Hokkaido for four days in mid-August and prepared at Ohashi gym in Yokohama, believes that he is better, too, and has the primary weapon to triumph again.

"Tenshin has good speed, but I don't think I lack speed [compared] to Tenshin," Inoue said. "[My] jab will be the key to winning the fight."

In his interim fight, Inoue bested former four-weight world champion Kazuto Ioka on the undercard of elder brother Naoya's successful defense of his Ring/ undisputed championship against Junto Nakatani on May 2.

"Ioka is a fighter with experience and great technical skill," he said. "I am satisfied that I was able to outperform him."

If he can complete the double over Nasukawa, Inoue hopes to go in search of more titles.

"I would like to do a unification bout against a champion from another organization," he said.

Nasukawa (8-1, 3 KOs) came to prominence after a standout MMA and kickboxing career. Soon to be 28, he engaged in an exhibition against boxing superstar Floyd Mayweather Jr. in 2018.

He reverted to boxing in April 2023. Since then, he has wins over Jason Moloney (UD 10) and Victor Santillan (UD 10).