Izanami, heartbroken by her split with her husband Izanagi, eventually returned to Yomi-no-kuni. In truth, after the split, she had caused quite a scene. Every day, she killed a fixed number of people in Izanagi's territories, while he created even more people daily. In this way, Izanami ultimately couldn't kill off the population on Izanagi's lands.
Such events, placed in modern society, are indeed common. A wife is accidentally disfigured and cannot recover, leading to her being abandoned by her cold-blooded husband. Although it's a common occurrence, for the abandoned wife, it feels like the sky has fallen in despair.
Back then, Izanami was in such despair that she returned to Yomi-no-kuni.
Later, a world fragment floated over the river in Yomi-no-kuni. As an innate deity, Izanami naturally understood the uses of such a fragment.
