According to Sidney Boquiren of The Boxing Bulletin and Ringwalk NIPPON, per Sports Hochi, the rare Japanese unification fight may be in negotiations between Hozumi Hasegawa and Fernando Montiel. If it does somehow come off, it's one of the better fights that can be made in the lower weight classes, with a pound for pound level fighter facing off against a three-weight titlist.
There are two reasons this type of fight has been rare in Japan. First is that the money isn't necessarily there. Hasegawa does just fine in pulling advertising market share while fighting the mandatories and fringe top 10 fighters that he's been facing. While Montiel is somewhat well known elsewhere, he's not a star by any means in Japan. The risk of this fight would be much greater, without any immediate reward of a bigger payday.
The second, more important, stumbling block is that the Japanese boxing commission only recognizes the WBC and the WBA. Montiel is currently a WBO beltholder, and for Hasegawa to fight him, he would need to seek an exception both from the WBC and the Japanese commission to face someone who is not ranked (since he's a champion of an 'illegal' sanctioning body.
According to Boquiren, both the WBC and the JBC are willing to grant this exemption, but it also means that if Hasegawa wins, he would likely be stripped of one of his titles very quickly. That could present a dilemma - either continue to do the same thing he was doing before, in which case the unification has no real benefit, or leave the comforts of home to try to build a name abroad, where Hasegawa would be permitted to defend his new belt.
Montiel potentially has more to gain than Hasegawa for this matchup. While he's won belts in three weight classes and has held one belt or another for almost a decade straight, he doesn't have tremendous name recognition, nor does he have an immense legacy. A win over someone Hasegawa's caliber may very well seal his ticket into the International Boxing Hall of Fame.
The final interesting dynamic is trying to get super promoters Bob Arum and Akihito Honda to work together on a fight. Neither promoter is known to make matches with outsiders where his cash cow has a legitimate chance of losing. For the fight to happen, someone will need to cede control, and someone will need to act out of character.
While there are quite a few obstacles to overcome, this could be a compelling battle if it does come off. And if it does, let's hope that they find a way to actually get the fight on the air on U.S. television.