Kousou (a Touhou LW original) refers to the formation of frost. This is an apt temperament for Cirno, the ice fairy who paid shockingly little attention to the scarlet mist. In addition to Water Phase and Star Essence, her unrestrained nature has led to her being imbued with Fire Phase. The flexible and patient Water Phase resists Metal Phase, because metal collects water, but it is weak to Earth Phase, because earth directs water. The diverse and uncooperative Star Essence resists the cooperative and indecisive Moon Essence, but it is weak to the charming and arrogant Sun Essence. The formless and passionate Fire Phase resists Wood Phase, because wood feeds fire, but it is weak to Water Phase, because water dampens fire.

The ability of Cirno from the world shrouded in overly scarlet mist (a Touhou LW original). It doesn't appear to be significantly different from Cirno's original ability. Since manipulating cold makes it easy to generate fog, she could likely keep the incident going for as long as she wanted. That said, doing so wouldn't interest her―assuming the idea even occurred to her in the first place, which it almost certainly wouldn't. The Sixth Prolonged Incident The Scarlet Mist Incident was originally resolved by Reimu and the others in a very short time. There was never any reason for it to drag on. As such, this prolonged version of the incident is found only in the false data. Some might argue that Cirno had cause to prolong it. After all, fairies love the excitement that incidents bring. But fairies also get bored incredibly fast. To them, the idea of the same incident dragging on is a total snoozefest. And while Cirno's ability lets her generate fog, she simply doesn't have the brain power to plot anything that lasts longer than an afternoon. Besides, what did she even stand to gain? Which brings us right back to square one. Perhaps Cirno should be ruled out as a suspect? What follows is mere speculation. Long ago, the Vampire Incident occurred. Like Remilia Scarlet during the Scarlet Mist Incident, the vampire responsible may have sought to block out sunlight. And if that plan also relied on a veil of fog, then perhaps Cirno's ability to manipulate cold was used to generate it. In other words, Cirno would have been a youkai possessed by a summoned demon. The idea of fairies being classified as youkai is supported by Cirno herself frequently being described as an "ice youkai." There are also several other related examples: Luna Child, the fairy of moonlight, said to be the most youkai-ish fairy; Clownpiece, who became as powerful as a true youkai through Junko's purification; Eternity Larva, who approached divinity through the door on her back; and the fairies and animal spirits that Zanmu Nippaku purified. None of this is enough to conclude that a fairy can become a god and then, in turn, become a youkai. However, it does suggest that shifts in a fairy's temperament can alter their state of being. Cirno may well have been possessed by a greater demon, used to cover Gensokyo in mist, and inducted as an official knight protector of the Scarlet Devil. Perhaps that explains her connection to the Misty Lake and why she lives there to this day. So why is it that Cirno, even powered up as an EX Being, doesn't display any demonic traits? Because she's just that much of a fairy. Listening to a devil whispering in her ear, confronting her innermost desires... Those sorts of things aren't really what Cirno is currently about. Her very nature prevents the demon from reclaiming control over her. In fact, she couldn't give the demon control even if she wanted to. And so, Cirno remains exactly what she has always been: Cirno. But ironically, the cold she unintentionally releases may be slowing down the incident's resolution.