Muranaka is by far the more well known. He challenged for the WBA Super Flyweight title last year, when he came up short against Kal Yafai, and prior to that had been the Japanese Flyweight champion, holding that title from December 2013 to April 2014, when he was stripped of the belt for failing to make weight. As a Flyweight Muranaka was a really good domestic level fighter, and could well have made a mark at Oriental or even world level. It was at that weight that he scored really good wins over Takuya Kogawa and Masayuki Kuroda, and scored a sensational 1-punch KO of Yusuke Sakashita.
At Flyweight Muranaka was an all action fighter, able to walk forward, use his physicality and fight at an incredibly high tempo. As he's gone up in weight he's found it harder to have the same success, opponents haven't been hurt by his shots, they've been able to take his pressure easier and have more success up close. This has been seen in narrow wins against Hiroyuki Kudaka and Ken Achiwa, as well as his loss to Khalid Yafai. Muranaka is still tough and has a great engine, but hs can no longer back fighters up in the same way, and fighters he's been fighting at Super Flyweight are now his physical equals.
On paper Saito doesn't look like he's fit to be fighting for a title, especially not one as highly regarded as the Japanese Bantamweight title which has been held by fighters like Shinsuke Yamanaka, Toshiaki Nishioka, Ryosuke Iwasa, Yasuei Yakushiji, Joichiro Tatsuyoshi and Yoshio Shirai. Despite that he's ranked #4 by the JBC and is a genuine contender on the domestic scene and also has one of the most misleading records in Japan. His 22 fight career saw him begin 2-3 before winning the 2012 Rookie of the Year, whilst fighting as a Super Flyweight. In the years since he has filled out his frame, been matched hard, and become a notable fighter on the fringes of the Japanese title scene whilst moving between Bantamweight and Super Bantamweight.
As mentioned Saito lost 2 of his first 3 bouts, since then he has gone 9-7-3 with losses coming to very good domestic fighters, such as Mugicha Nakagawa, Takayuki Okumoto, Yushi Tanaka, Naoya Okamoto and Ryo Akaho, in what was also a Japanese Bantamweight title fight. His team have matched him hard, and even in those losses he has been competitive, with Nakagawa the only one to take a clear decision over him and even against Akaho he was very competitive being being stopped in round 9. With that in mind it's fair to say he deserves to be in the mix, especially given that the top fighters in the country have progressed beyond domestic level already.
Coming in to this Saito will be the under-dog, but we genuinely think he'll be a handful, and although he should be regarded as the under-dog he is a very live under-dog, and we wouldn't be surprised by the naturally bigger man picking up a narrow decision win.
Unfortunately the Japanese Bantamweight division, at least domestically, is a big lacking right now, but with the likes of Kai Chiba, Fumiya Fuse, Ryuto Owan and Kazuki Nakajima, among others the division is maybe only a year or two away from being red hot, like it usually is.