There are two official Ys games released under the name "Ys IV": Mask of the Sun, made by Tonkin House, and The Dawn of Ys, made by Hudson Soft. While both games share the same setting, Hudson Soft took more creative liberties with The Dawn of Ys' presentation, resulting in two different games. Originally, The Dawn of Ys was the canonical version of Ys IV. This was changed following the release of Ys Vi: The Ark of Napishtim, wherein Mask of the Sun became the canon version. Years later, however, both versions would be rendered non-canon with the release of Ys: Memories of Celceta, which is not only also considered "Ys IV", but was actually made by series creators Nihon Falcom.