Japan's Naoya Inoue announced Thursday that he will fight Britain's Paul Butler in December when all four bantamweight world championship belts will be at stake.

The 29-year-old Inoue, nicknamed "Monster", holds the WBC, WBA and IBF bantamweight belts and is aiming to become undisputed world champion by capturing Butler's WBO title on December 13 in Tokyo.

"I want my name to go down in international boxing history, and to change Japan's boxing history," the unbeaten star said at a press conference to announce the showdown.

"Paul Butler is an extremely well-rounded fighter, with no obvious weak points," Inoue said.

"In the fight, I want to weaken him little by little with my boxing, before taking him down.

"I will demonstrate the overwhelming difference in strength between us, and unify the four organisations."

A victory would make Inoue the first undisputed world champion from Asia and only the ninth since the four-belt era began in 2004.

Earlier this year, Inoue became the first Japanese fighter to top Ring Magazine's prestigious pound-for-pound rankings as the best fighter across all weight divisions, before dropping to second behind heavyweight champion Oleksandr Usyk.

Inoue repeated his aim to move up from bantamweight (118lb, 53.5kg) to super-bantamweight (122lb, 55kg) after he unifies the belts. He has said previously that he will retire when he turns 35.

"I've always said I want to fight to unify the four championship belts. This will be the final chapter of my career in bantamweight and the start of super-bantamweight," Inoue said.

"This is not the goal. It is only a passing point. I am still trying to aim higher. This will be a fight for me to bring my career to a higher level."