While the pieces have relatively simple polygons to them, the variety of textures might be difficult for someone new. If you want to go about doing it yourself, blender offers a great free tool for modeling. You can also do a lot of the work yourself in UE4: Use BSPs to create a board and a piece, then apply textures and decals to the materials of the piece based on an ID.
That said, if you’re like me, then sometimes the opportunity cost of modeling your own stuff is outweighed by the alternative uses of the time. For as little as $10, you can go to http://www.turbosquid.com/Search/Index.cfm?keyword=shogi and purchase a pre-modeled and textured board, and focus on the programming aspect to get to a finished product faster, which can offer you the incentive to improve your own modeling skills at a later time to develop the game further. Hope that helps!