The Great Collapse (大崩壊 Daihoukai) is a catastrophic apocalypse that happened long before the events of the Kiseki Universe. A continental-scale crisis that shook all of Zemuria that led to the destruction of its ancient civilization and all survivors plunged into the Dark Ages. The event marked the start of the Septian Calendar.
As the event marked the end of everything before the Collapse, remnants (like ancient races, artifacts, and relics) managed to survive and were buried and scattered throughout Zemuria. The Church's Congregation for the Sacraments took action upon retrieving those artifacts for research and becoming the inspirational basis for the Orbal Revolution technology, thus the order of the Gralsritter was founded.
- Aidios's Tribulation: According to the Septian Church, the Congregation for Divine Worship theorized that all might have been a trial by the Sky Goddess, Aidios. To test humanity's progress on life, perspectives and the infinite cycles of life, where humanity learned through the dark ages. The Septian Church believes that in every turn, the world renews for the better.
- Natural Disaster: No specific proof discovered sofar, but some Zemurians assume the Collapse to be just a huge natural disaster.
Pre-Septian Calendar (B.S)
- The Gods of the 2 pillars and their respective followers have descended and encountered. The gods fought and mutually killed each other after a 1000 days struggle.
- Aidios the Sky Goddess gave humanity the Sept-Terrion, seven sacred treasures which granted dominion over the land, the sea and the skies. They were eventually separated dividing humanity to pursue the respective ideals.
- Only Ragnard is the "last" survivor of the Ancient Dragons into the Septian Calendar era.
- Somehow in Ao no Kiseki, the Azure Demiurge's ultimate craft "Spacetime Collapse (時空大崩壊)" is based from this concept. Cause once the craft activates, its instant kill to all party members, and an automatic game over.