Ys IV: Mask of the Sun

Mask of the Sun was released in 1993 and was one of two games released under the title of "Ys IV", the other being Hudson Soft's Ys IV: The Dawn of Ys for the PC Engine. The two games share the same basic story, but many changes were made in the Hudson-produced Dawn of Ys. Of the two, Mask of the Sun was the official Ys IV storyline before the release of Ys: Memories of Celceta. Originally a version of "Mask of the Sun" was also planned by Sega for Mega Drive and later Mega-CD under the Sega-Falcom joint development agreement, but this version was ultimately canceled.

In 2005, Taito Corporation developed a remake of Mask of the Sun for the PlayStation 2, titled Ys IV: Mask of the Sun - A New Theory.

Ys IV takes place between the events of Ys II and Ys III: Wanderers from Ys.

After returning to the town of Minea, Adol comes across a message in a bottle. The message is from the far-off land of Celceta, asking for help. Adol decides to take the offer and boards a ship to the land of Celceta.

In this version of Ys IV, Adol's departure occurs immediately at the start of the game; there are no initial events occurring in the actual town of Minea, as there were in The Dawn of Ys.