Ono may not be a name many outside of Japan are familiar with but he is a former OPBF champion and is currently ranked by 3 of the 4 title bodies. That includes the IBF who have him at #14 at Light Flyweight as well as the WBC who have him at #5 and the WBA who rank him #12.
Of course Ono would have to drop down to fight for Katsunari's title though we don't imagine that will be a struggle considering their will be a world title on the line.
As for Katsunari this would the second defense of the IBF title he won last year in Mexico. Given the tough match ups that Katsunari has been in we have no issue with him having a supposedly "easy" defense before moving back to facing the divisional elite. Unfortunately for him however a title unification with Xiong Zhao Zhong, which was spoken about a lot last year, is of course off the table now that Zhong is no longer a world champion.
It would likely that if Katsunari beats Ono he'd then chase a showdown later this year with WBA title holder Hekkie Budler in what would be a genuine super-fight at 105lbs and a major unification.
(Photo courtesy of http://www.l-kid.com)