One thing we knew was that Yamanaka would be defending his world title in April against a yet to be named opponent in Kansai. What was hinted at however was that that defense may be his last with the popular fighter talking about giving up his Bantamweight title to chase bigger riches at Super Bantamweight.
More than just moving up in weight the suggestion is that Yamanaka would be challenging for a title in the US, or more precisely Las Vegas. This would suggest that Yamanaka is looking seriously at fights against either Leo Santa Cruz or Guillermo Rigondeaux, both of whom would make for great opponents for Yamanaka.
When asked about a possible unification with WBO champion Tomoki Kameda, Yamanaka seemed to suggest that that fight would be unlikely. It wasn't that the WBC champion doesn't want that fight but he seems to realise that the youngest of the Kameda brothers is unlikely to be willing to share a ring with him.
Yamanaka will be traveling out to the US at the end of this month in preparation for his April title defense. It's fair to assume that whilst he's over there he will be scouting possible opponents, including Leo Santa Cruz who fights on March 8th, and trying to get used to US conditions. Don't be shocked if you see Yamanaka ringside for at least 1 big US bout in early February.