Outline of the Black World was established by Dingir Ereshkigal. In order to simulate "supreme ruin", Energeia was repeatedly copied and deleted countless times.
All in order to dye the Energeia with "supreme ruin".
Nevertheless, even Dingir who lives in eternal time has their own limit in repeating similar works. The Dingir, who suddenly snapped, renounced the domain assigned to her. By chance, the fate of Black Word is decided.
The world abandoned by the Dingir, without any involvement from the Dingir, developed differently from the Dingir intention. A world where although the concept of death remains largely in control, was saved by a gentle brothers before the Divine Progenitor of Seven Deadly Sins spreads disaster. A world where the surviving Archangel Uriel decided to not kill the dying Seven Deadly Sins of Wrath Satan, and spend the rest of his life in a foreign land.
The younger brother gave up his holy spirit, merged with his elder brother and took the name of Atomasukaya, and then disappeared from the history.
However, he is still alive. He evaded the influences of the descendant of the Seven Deadly Sins who brandished their authorities, and keeps a watchful eye on the security of his own castle. The surrounding area later became the sole completely autonomous region, and before one knows, became known as "Tombcastle"—the resting place of the Divine Progenitor.
Now, the castle is inhabited by 7 girls who inherited their leader status from the founder Atomasukaya. Compared to the other area of Black World, land near the castle is inhabited by a large number of opportunistic Diabolus and Nosferatu, who have settled around the Tombcastle which is overwhelmingly safe and comfortable. This is the reason why "nobody who headed to Tombcastle has returned".