Ys: Memories of Celceta on PC is a re-release of 2013s PS Vita release, now available on Windows PC with quite the graphical upgrade and not just resolution. This game is a replacement for several others made by different developers called Ys IV. There were two games back from the SNES and TurboGrafx-16 days, titled ‘Ys IV: Mask of the Sun’ and ‘Ys IV: The Dawn of Ys’ that claimed that title, and there was a PlayStation 2 era remake called ‘Ys IV: Mask of the Sun ~a new theory~’. None of these releases were made by Falcom, and none of them made it out of Japan. Now we are given both a remake and a sequel Ys: Memories of Celceta. To emphasize that this is really a new game set in the setting of Ys IV, they decided to drop the ‘IV’ part of the name.
Source: N4G PC Ys: Memories of Celceta review – ChristCenteredGamer