Squall Line (a Touhou LW original) refers to a thunderstorm composed of multiple cells where new cells form as others dissipate along a single gust front. This is the temperament of this Yuugi, who supports the New Land of the Oni as a Nio oni. Yuugi's original temperament of Metal Phase (strong against Earth Phase but weak to Fire Phase) and Star Essence (strong against Moon Essence but weak to Sun Essence) have combined with her guardian azure dragon's temperament (strong against Wood Phase).

The ability of Yuugi Hoshiguma 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. Yuugi'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 Yuugi and Kasen 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. According to the historical records of most worlds, following the Battle of Mount Oe, the oni left their mountain and descended to Hell in resignation because humans no longer feared them. If these records are taken as fact, the migration of the oni could have played out in one of the following ways: 1. Suika Ibuki and the other Big Four, who previously ruled Gensokyo's Youkai Mountain, came to Gensokyo after they left Mount Oe. But then they once again got fed up with humans in Gensokyo and migrated to Hell, which would later become Former Hell. 2. Mount Oe was part of the group of mountains collectively known as the Youkai Mountain, situated within the original bounds of Gensokyo. This would mean that at the Battle of Mount Oe, Suika and the other oni were already the Big Four, and the battle is what caused them to grow weary of humans and migrate to Hell. 3. The oni took another path from Mount Oe to Hell. The second theory may seem pretty out there at first glance, but when you consider how the Youkai Sage can manipulate boundaries, it's possible that the original Gensokyo, not enclosed within a barrier, was a patchwork of multiple locations spread across Japan. Also, while the Youkai Mountain appears as a single mountain within Gensokyo, it could be an amalgamation of many outside-world mountains described as being home to youkai in tales and legends. This is basically the opposite of the legend of the Yatsugatake Mountain Range, which is said to have originally been one massive mountain before Mount Fuji smashed it into pieces, giving it eight smaller peaks. There are many examples of foreign buildings or youkai entering Gensokyo with complete disregard for the distance it should take to get there. This might also help to explain why a modern-day city could be seen through a gap in the barrier that appeared at Hakurei Shrine, even though Gensokyo is supposed to be surrounded by mountains. This world's Yuugi and her fellow oni didn't go to Gensokyo, or rather, they couldn't. Having grown weary of humans after the Battle of Mount Oe, they decided to try to build a New Land of the Oni. However, it is unclear where they lived before they came to Mount Oe and where they migrated after the battle. There were lots more oni in the past, so perhaps they all came together from different places and dispersed afterward. Perhaps some lived as Yaksha or Rakshasa in far-away India, whereas others served as guards in Hell as kishin. Some of them might even have spent some time in China, where oni are referred to as spirits of the dead or gate gods according to the philosophy of yin, yang, and the Five Phases. There might also be oni who were labeled as "people who do not obey" during the time when the imperial court spread its domain to the other islands of the Japanese archipelago. Creatures such as giants and dragons said to inhabit far-away Europe were also referred to as oni, not to mention the Europeans themselves, who the Japanese also labeled as oni due to their unfamiliar appearance. In ancient Japan, greater beings or beings that could not be seen were called "onu," a term that later became conflated with oni. The term "oni" encompasses many non-human entities, and there have always been oni for as long as there have been humans. Unexplainable Phenomena The unexplainable nature of oni and other youkai is an integral part of what defines them as youkai. It's predicted that this world's Yuugi (i.e., Hoshiguma-Douji) uses her ability to ensure a peaceful life for the oni as Shuten-Douji's left hand.