The Great Spirit War
The Nihilic Scriptures detail a war that occurred some time after the creatures of Nihilo were pulled from the Soul Weave. The major antagonist figure, Aramis, pitted Youkai against the helpless creatures and their creators. It is claimed that Aramis had developed a method of manipulating creatures before death, as well as capturing souls before Nagi could cleanse them and transmuting them into Youkai.
It is unclear what role of the deities worshiped in Nihilo at present time played during the Great Spirit War. Some believe they were absent most of the time or that they had no power because they were not worshiped. Others believe they had helped the creatures of Nihilo as best they could, charming and protecting those within their domains.
When the war for the creatures of Nihilo was at its darkest hour, The Divine Emperor assisted Nami in creating several powerful and talented creatures known today as the Zodiac Souls. The Nihilic Scriptures claim that these creatures contain a thread of The Divine Emperor himself and are thus impervious to the swayings of Aramis and were able to fight the Youkai with skill and ferocious tenacity.
The tide of war had changed and Aramis was defeated. Dust settled, the war was over. Aramis was tried and punished for his crimes against creation, banished to the Nine Hells. At the same time, The Divine Emperor fell into a deep slumber as assisting Nami had drained him of much of his energy. The Nihilic Scriptures detail his return again when the world needs him the most. Some have theorized this to be a sort of doomsday prophecy as he and the Zodiac Souls will reappear when Nihilo is about to break once again.