Undefeated Japanese boxer Naoya Inoue announced his decision Friday to relinquish all four bantamweight belts and move up to the super bantamweight division.

In a press conference in Yokohama, Inoue said his attempt to become the world's first boxer to sweep the WBA, WBC, WBO and IBF belts in two weight divisions would be his biggest challenge.

Japanese boxer Naoya Inoue poses for photos with his WBA, WBC, WBO and IBF champion belts in Yokohama, near Tokyo, on Jan. 13, 2023. (Kyodo)

"The real battle starts from here," Inoue said. "I'm very excited."

The 29-year-old, nicknamed "Monster," completed a sweep of the four in the bantamweight class last month with an 11th-round knockout of Britain's Paul Butler, who came in as the World Boxing Organization's bantamweight champion.

"I'm confident that I can take on top-level super bantam boxers, even at present," Inoue said. "But it will take a while to make myself really unbeatable."

Inoue has won championships in three different classes, having previously moved through the light flyweight and super flyweight divisions.

He became the first Japanese to top the pound-for-pound rankings published by the prestigious Ring magazine in June 2022 and now has a 24-0 record, with 21 knockouts.

As for Inoue's next opponent, his boxing gym chair Hideyuki Ohashi only said, "It's under discussion."

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