MSX2, PC-88/98 and Sharp X68000 versionsEdit
Gaias was recruited by Rogles at an unknown point of the past and nothing about him is known during the first game's events. After his master's death and Megas's rising, Gaias, along with Zaluga, another of Rogles's survivor generals, formed a resistance to Megas' regime. While Zaluga went to search for the Valis sword in the human world, Gaias searched for the Phantasm jewel in the Dream world. Although Zaluga died in his mission, Gaias was successful in finding the artifact he was searching for. Megas and his army soon found out that Gaias had the Phantasm jewel and sent general Haizen to take it from him. Meanwhile, Yuuko tried to open her way to Vanity but was stopped by Gaias's soldiers and shortly after fought Gaias himself with a Rogles statue powered with the Phantasm jewel itself. After being mortally wounded, Gaias could not fight anymore. He told Yuuko about Megas's terrible actions and tried to give her the Phantasm jewel, but died when trying to do so as the jewel was taken by Haizen who arrived there in that moment.
PCE-CD/TGCD version and Valis SD/Syd of ValisEdit
In this version, Gaias's role and appearance are significantly changed. He is one of Megas' generals and the one who was sent to invade Vanity's castle with his soldiers in order to kill Valia to leave Vanity's forces highly decreased. Although his mission was successful, Yuuko tried to help Valia and found him in the way. They fought and Gaias lost. Before dying, he warned Yuuko that although he was defeated, Megas's enemies were going to fall.
In the MSX2, PC-88/98 and SX68 versions of Valis II, Gaias is portrayed as a loyal soldier to Rogles, so loyal that he built a statue of him. He is a noble warrior although as he decided to fight until death and when he knew he was going to die because of the wounds Yuuko gave him, he recognized his defeat and tried to give her the Phantasm jewel.
In the PCE-CD/TGCD version and Valis SD/Syd of Valis, Gaias is an enthusiast and decisive warrior with a great desire for fighting. He likes to have powerful opponents (even to the point that, when he died, he was smiling while congratulating Yuuko for being so strong) and obeys Megas' orders without questioning.
In the MSX2, PC-88/98 and SX68 versions of Valis II, Gaias can levitate, moving at high speed and shoots thunder beams from his hands. He is also shown to be a good builder as he perfectly designed a Rogles statue that also serves in combat.
In the PCE-CD/TGCD version and Valis SD/Syd of Valis, he can launch missiles from his back and make them fall in diagonal or vertical patterns at slow or fast speeds. He can also charge forwards or backwards of his opponents and shoots a mechanical dragon-like missile from his stomach that can chase Its targets.
Gaias appeared in all versions of Valis II as a Rogles's general in the MSX2, PC-88/98 and SX68 versions and as a Megas's general in the PCE-CD/TGCD version. He also appears in Valis SD/Syd of Valis with the same aforementioned role. In all of this games, regarding his role, he is the third boss.
Gaias also appears in Valis IV in one of Yuuko's flashback images.
- Gaias is the only character from Valis II to change his role between versions.
- Even thought his role changes, his position as the third boss is never changed in any version where he appears.
- Gaias's role from the MSX2, PC-88/98 and SX68 versions is taken by Gillian in the PCE-CD/TGCD version.
- In his PCE-CD/TGCD version's artwork, Gaias holds an axe that he never uses in-game.
- Gaias is the only boss in the MSX2, PC-88/98 and SX68 versions aside from Megas to use an animated offensive object (Rogles statue) to fight against Yuuko before facing her personally.
- Due to the differences he has between versions, some fans refer to the MSX2, PC-88/98 and SX68 versions' Gaias as Gaiyus and the PCE-CD/TGCD one as Gaias.
- Gaias is referred to as Ghyah in the Syd of Valis's manual.
- Gaias is the character with the most known weight. There are many other characters with presumably much more weight but their exact numbers are unknown.