Super Robot Wars/Masou Kishin III/Story

Upon the developments of spirit enhancement and beliefs in spirits, religions have mostly disappeared from the people of La Gias. Gods only exist within stories and mythologies. Only the three gods: God of Destruction - Sava Volkruss, God of Harmony - Ruzamno Lasfitot, and God of Creation - Gizos Gragios still have followers with deep faith remaining until present.

During the time dinosaurs existed on the upper surface, La Gias on the other hand had a great civilization of giants...and they are far more intelligent and advanced than humans. Some of the giants even advanced to the upper surface. So, they were too drowned in their modern civilization altered the surrounding environment, causing distortion in earth's balance.

Then sent from the heavens/skies is a hero named Gizos Gragios destroyed the giants and brought new life to La Gias. Around the same time humans started to exist on above ground, the grudge of the dead giants grew larger over time and became one, the being called Sava Volkruss. Volkruss then starts bringing chaos and destruction to La Gias in a variety of incarnations and forms.

Although it entered many fierce battles with Gragios, finally during 1500 years ago. Volkruss finally appeared in its true form before entering the final holy war with Gragios, and also the last Gragios descends. Volkruss is defeated and its power divided to five and sealed around Langran.

Then there's the talk about how the presence of the God of Destruction and giants was confirmed, but the God of Creation has its existence questioned due to the lack of convincing evidence.