By Jake Donovan

A stacked tripleheader in Japan is now without its centerpiece attraction. has learned that reigning junior flyweight titlist Felix Alvarado is forced to withdraw from his planned title unification bout with unbeaten Ken Shiro. Their two-belt fight was slated to take place Dec. 23 in Yokohama, Japan, but Nicaragua’s Alvarado is no longer able to go through the bout after failing to shake a lingering ailment which plagued him even prior to opening training camp according to a report from Telenica/Canal 8’s Levi Luna, who was first to report the development.

“My manager William Ramírez spoke with the (promoters) in Japan and notified them that I am not able to be 100% ready for the fight,” Alvarado (35-2, 30KOs) told Telenica. “Señor William made the decision and the people of Japan agree.”

 News of the development was confirmed by Alvarado's handlers. 

 "Unfortunately, that is correct," Ramírez told "Felix has been unable to train due to a bronchial problem, therefore the fight is in jeopardy.” 

 The latter part is in regards to whether or not the bout will be rescheduled, or if Japan's Shiro (16-0, 9KOs) plans to remain on the Dec. 23 show, which would push back any such plans for the unification bout.

 Alvarado first felt ill at home in Nicaragua before opening training camp in Miami. Inability to properly breathe after training sessions prompted a team discussion to pull from the event. Not being at full strength for Shiro—arguably the best junior flyweight in the world—is hardly a sound game plan to face him, although the greater concern is for Alvarado’s well being.

“It was a mutual agreement with my team and my manager,” noted Alvarado, who was looking at his third straight title fight on the road.

The 30-year old from Nicaragua—whose twin brother Rene (31-8, 20KOs) challenges Andrew Cancio for the 130-pound title this weekend in Indio, California—traveled to Philippines to win his 108-pound belt, scoring a 7th round knockout of Randy Petalcorin last October. His lone successful title defense to date took place this past May, outpointing Reiya Konishi on the road in Kobe, Japan.

Conceding hometown advantage to Shiro was never an issue, but entering such a bout at less than full strength was a dealbreaker.

“I could never train one hundred percent since I came to Miami, because the climate change affected me,” admitted Alvarado.

Sources have informed that the balance of the show remain intact. Local hero and 2012 Olympic Gold medalist Ryota Murata (15-2, 12KOs) will face Canada’s Steven Butler (28-1-1, 24KOs) in the first defense of his second tour as a secondary middleweight titlist in the evening’s main event. Also still on the show, road warrior Moruti Mhtalane (38-2, 25KOs) defends his flyweight title versus former three-division champ and all-action cult favorite Akira Yaegashi (28-6, 16KOs).

Whether or not Shiro will remain on the card versus a replacement opponent has yet to be determined. The unbeaten titlist from Kyoto, Japan looks to make the seventh defense of his title, although sources have alerted that there is preliminary discussion to reschedule the unification bout with Alvarado. 

Jake Donovan is a senior writer for Twitter: @JakeNDaBox