The issue, an injury to his right hand suffered in his win over Omar Andres Narvaez, has been very slow to recover. It's now thought that he will be out of the ring until August, at the very least.
Inoue's promoter, Hideyuki Ohashi, has raised fears even further suggesting that if surgery is needed then the recovery for the young power puncher may be delayed even further with some speculating he may actually be out of the ring for the rest of the year.
From what we understand the the problem is with the back of his hand and although it's not thought to be career threatening the recovery is taking much longer than hoped. It is thought that surgery won't be needed, at least yet, though if the injury does reoccur at some point it could be another spell on the sidelines. In regards to deciding on whether or not surgery will be required Inoue will have inspection of the hand next week and a decision will be made soon afterwards.
At the moment Inoue has been allowed to practice in the gym though has been limited to practicing only with his left hand and doing various other training that won't risk the hand.
Disappointingly it seems the mooted super fight between Inoue and Roman Gonzalez (41-0, 35) won't be taking place this year. If Inoue is out for any long stretch we can't see him jumping straight back in with a fighter like "Chocolatito". Instead it would seem likely that he'd face a mandatory challenger, probably the winner of the upcoming bout between Warlito Parrenas (23-6, 20) and Jamie Conlan (13-0, 8), and then another possible foe to help prepare for someone like Gonzalez.
At just 21 years old it's a shame Inoue has got such a serious injury however the relief is that he's young enough to come back from it and likely come back a better, more rounded fighter upon his return to the ring.
Related story- Naoya Inoue see's first defence of WBO Super Flyweight title delayed due to hand issues
(Image courtesy of Hideyuki Ohashi's blog)