Ys IV: The Dawn of YsPC-Engine Super CD2 Japanese (NTSC-J) Games
Oddly, there are two different Ys IV games, this one for the Super CD, and another one for the Super Famicom. While according to Falcom, the Super Famicom version is the 'real' story, the Super CD game is arguably the better game. If you like Ys, you'll need this game to complete your collection!
Used Ys IV: The Dawn of Ys (good case, good instructions)