The Great Cataclysm (大災害, Daisaigai) is an event that happened two hundred and fifty years before Year 198. The incident involved flames exploding around the world, devastating it and leaving most parts of the planet uninhabitable. Continents were torn apart and some nations were utterly obliterated. As a result, survivors fled to the Tokyo Empire, which remained mostly stable during the period.
The flames that brought this destruction upon the planet was the Adolla Burst. Along with Raffles I guidance, The Holy Sol Temple, Haijima Industries and Vulcan's ancestors collaborated to create the Amaterasu generator, enabling sustainable and nation-wide power for Tokyo to utilise. This power let the Empire develop further and allowed for more migration from the outside world. This lead to cultural changes within the Empire, such as it becoming customary to refer to others by the first names as opposed to their family names.