The 19 year old Yamada, widely regarded as one of the best young female fighters on the planet, has been sparring with WBC Atomweight champion Momo Koseki (17-2-1, 4) and as a result has been getting arguably the best sparring she could in and around her weight.
Koseki, who has held the WBC Atomweight title since 2008, is similar to Hong in several ways. Firstly they are both around the same height with Hong standing at 5'3" whilst Koseki is 5'4" and secondly both are southpaws. Stylistically they are different, of course, though those 2 features of Koseki are likely why Yamada has picked her as a sparring partner.
Yamada, who knows she'll be in for the toughest test of her career when she takes on Hong, will know that this level of sparring is invaluable to help her cope with the skills of the champion. Unfortunately however no level of sparring can prepare you for needing to travel to a champions backyard which is exactly what she'll be doing when she meets Hong in February. If she can perform well with the crowd against her, then Yamada could well announce herself on the world stage as a major force in and around the Minimumweight division.
Hong, who has been the WBO world champion since June 2012, will be seeking the 3rd defense of her title when she meets Yamada in Chuncheon.