According the JBC these two are the top two contenders in Japan. Going in to the fight Kawaguchi it the #1 ranked fighter and Masuda is the #2 ranked fighter though this says a lot more about the Japanese Bantamweight scene than anything else.
As we know the top Bantamweight in Japan is Shinsuke Yamanaka, the WBC champion, behind him is Tomoki Kameda, the WBO champion and closely behind them is Ryosuke Iwasa, the OPBF champion and around the same level is former world title challenger Ryo Akaho. Basically Japan has 4 world level Bantamweights domestically however they struggle as a result and the domestic scene is rather weak.
Of the two fighters actually involved here we tend to feel that the 31 year old Masuda is the slight favourite. Firstly he appears to have mixed in better company with fights against both Iwasa and current Super Bantamweight champion Hidenori Otake. Although he lost to both has has been fight on and around the top of the Japanese domestic level for a while.
Whilst Masuda has faced two really recognisable names it's fair to say that Kawaguchi has only faced one on the same level, Yasutaka Ishimoto. He has also faced Jerope Mercado, but it's certainly Ishimoto that stands out and he actually beat Kawaguchi.
Interestingly both of the men have dipped their toes at Super Bantamweight as well as Bantamweight and whilst neither man should struggle to make 118lbs it still needs to be a point of consideration, especially when you consider that Kawaguchi hasn't weight 118lbs or less since 2009. To make the weight again could take something out of him though we're not expecting it to.
With both guys having, at best, moderate power we expect to see this bout going to a decision and with what we know of both it's going to be a close one with neither guy having the skills to clearly dominate the other.
In all honesty we're unsure who will win but we don't expect more than a round a two will separate the men in what promises to be a very interesting encounter, even if the winner won't crown the best Bantamweight in Japan. We're a guessing a split decision with Masuda the winner but this bout really is a toss up.
(Poster courtesy of http://green-tsuda.com)