Well the best place to get the PS2 versions of Ys IV and V would be through an import site such as play-asia or national console support (NCSX). But they do not have them in English... yet. There is still no confirmation that these Taito remakes of Ys IV and V are ever going to be released in English and considering the sales of Ys VI in American and European markets it might not be coming.
If you want to play the Ys IV and V games in English the best way is to use an emulator for SNES games and an emulator for PC-Engine (Magic Engine works well) games since the only two translated versions of Ys IV are for these two console systems and were fan-translated. There are two very different versions of Ys IV and most consider the PC-Engine version to be a superior adventure.
You have two choices: Ys IV: The Mask of the Sun for SNES (Translated by Aeon Genesis)
or Ys IV: The Dawn of Ys for the PC-Engine (Translated by Nightwolve)
Currently there is no English version of Ys V for the SNES, so you'll have to play that in Japanese if you wish to play it. The translation group Aeon Genesis is and has been working on an English version patch, but have not made progress on it in quite sometime, and when I keep asking them about the patch they've ignored my questions, so that leads me to believe that they are not considering this project at all right now. It may be a very long time before we are able to see Ys V in English.
-SkyeWelse
