Zui-un (a Touhou LW original) refers to shining clouds that appear as a good omen. This is an apt temperament for this Kasen, who supports the New Land of the Oni as a Nio oni. Kasen's original temperament of Metal Phase (strong against Earth Phase but weak to Fire Phase) and Sun Essence (strong against Star Essence but weak to Moon Essence) have combined with her guardian white tiger's temperament (strong against Wood Phase).

The ability of Kasen Ibaraki from the world of iron and steam (a Touhou LW original). Those who reside in the world where mountain resources are converted to power have formed their own unique civilization. Kasen's ability doesn't appear to have changed much, but she seems to have used it extensively to establish the civilization she's a part of. This world's Kasen and Yuugi work to support Suika as the two Nio oni. In our world, these three are all known as members of the Big Four of the Mountain, but things are a little different in this world. One difference being that the fourth member of the Big Four is nowhere to be found. "Nio" is nothing more than a title used to refer to two people in much the same way as "Big Four" is used to refer to four. What's special about this world's oni is that their traits have intensified due to them roaming outside the flow of history. Humans began keeping written historical records in earnest when they formed permanent settlements. On the other hand, tribes who continued to wander the land didn't do so, making knowledge of them more elusive. The oni may have been one such tribe. Around a thousand years ago, during the Heian era, Shuten-Douji and her band of oni roamed the land between Kyoto and Mount Oe. Each night, they ran amok. It's thought that Kasen, who at the time, went by Ibaraki-Douji, was part of this group. Where she was before this time is unclear. Different legends give different locations for her hometown, but equally, she may have been in the Land of the Oni, Hell, or some other world entirely. Shuten-Douji's group disbanded after an oni extermination known as the Battle of Mount Oe. It's said the oni despaired at the humans, who had stopped fearing them, and retreated to Hell. Ibaraki-Douji, on the other hand, fled the Battle of Mount Oe, only to later lose her arm in combat against a certain samurai... or so the story goes. However, the life of this world's Ibaraki-Douji did not follow that path. She never lost her arm, nor did she arrive in Gensokyo. She didn't even become a hermit. That said, there's still one thing that doesn't make sense. Shuten-Douji―also known as Suika Ibuki―was supposedly defeated, but Kasen and Yuugi continue to serve her. It's as if the Battle of Mount Oe never happened. It's as if they're reliving a happier time in the present. The oni decided to take the youkai who served them and establish a new Land of the Oni. Using their own sense of time and abilities, they created a spiritual civilization―one that was fundamentally different from any human civilization. Having distanced themselves from humans, the oni could no longer sustain themselves on human fear, so they had to find another energy cycle to harness. As a result, they created a new system of faith. This system reverted their existence to the time before gods and oni diverged and redrew the line distinguishing humans from non-humans. Suika Ibuki, whom Kasen and the others serve, made this possible. Using geothermal energy, she warmed the land, turning it into a hot spring town, which became the New Land of the Oni. Metal was deemed necessary to withstand the town's high temperature and pressure and rule over the land, so a huge quantity of it is consumed each day. The New Land of the Oni is an economic society built on the supply of geothermal energy, the production and distribution of metal, and the currency of faith. This secret hot spring town is kept afloat by those three things. But remember, all of this only exists because of their failure to reach Gensokyo. In modern material civilizations, the term "animal" refers to certain species of living creatures as designated by the study of biology. However, in sophisticated spiritual civilizations, "animal" has a broader meaning and encompasses all beings with an anima. It's predicted that this world's Kasen (i.e., Ibaraki-Douji) uses her ability to help lead the oni as Shuten-Douji's right hand.