Negotiations for the mouthwatering four-belt unification super-bantamweight clash between Filipino Marlon Tapales and Japanese Naoya Inoue have been progressing and both camps appear headed to an agreement for a December date.

Reporting from Tokyo, Sean Gibbons, who represents Tapales, told Daily Tribune that talks are doing well.

"In the ball park," Gibbons said from the Japanese capital on Wednesday afternoon.

Inoue holds the World Boxing Council and World Boxing Organization belts while Tapales dangles the World Boxing Association and International Boxing Federation straps.

Gibbons has been constantly meeting with Akihiko Honda, who calls the shots for Inoue, and even with Inoue's manager Hideyuki Ohashi.

If everything falls into place the scheduled 12-rounder will take place at the Ariake Arena.

The exact date in December is still up in the air.

Inoue became the WBC-WBO champion after knocking out Stephen Fulton of the United States last July.

Tapales had taken the WBA-IBF crowns last April when he scored a hard-earned 12-round split decision over Murodjon Akhmadaliev of Uzbekistan in San Antonio, Texas.

In anticipation of a tough battle, Tapales has been training in Las Vegas the past few weeks.