Sakufuu (a Touhou LW original) refers to the north wind. Unlike the other kaiju created by Yuuka Kazami, this Letty is not endowed with the temperament of a celestial object. This probably has something to do with how Letty is a Mark 0 kaiju―the first batch of kaiju Yuuka made. This Letty is resistant to Fire Phase, so it seems she has retained an intense cold temperament. However, her resistance to Star Essence is more mysterious since Star Essence (diverse and uncooperative) is the temperament of kaiju. This might indicate that the kaiju were initially created for some purpose other than combating the Capital or the rebels.

The ability of Letty Whiterock, the kaiju (a Touhou LW original). This ability is significantly different from the ability of our world's Letty. The professor made the Mark 1 kaiju when she discovered how to imbue kaiju with abilities and memories. She created the Mark 2 kaiju after she worked out how to find more efficient and effective ability combinations. However, the first kaiju she created were the Mark 0 kaiju. This world's Letty Whiterock is a Mark 0. Since they came before the Mark 1s, they were greatly flawed when they were first created and were only imbued with abilities and memories much later. That's why the professor didn't initially incorporate the Mark 0 kaiju in her plans. However, she later decided to awaken them in order to further her research. This was the first time she had ever asked someone else for help. At first, the professor only sought the ability to cool things down. She didn't consider any of the possible applications of such an ability, merely wanting to ensure that her first-ever kaiju could do something unique. However, Letty's ability is only capable of amplifying the winter chill. It was next to useless in this world where the concepts of seasons had all but ceased to exist. Letty was sorry that she couldn't be of more help, but the professor lovingly nurtured her ability. After much trial and error, Letty's ability was finally complete. Now, Letty secretly wishes to return the favor by learning how to artificially induce hibernation to extend the professor's life. It seems apparent that this world's Letty was imbued with the ice fairy Cirno's ability. With it, she can create cold out of nothing, which, taken to the extreme, is basically the same as creating winter. This, combined with Letty's inherent ability, gives her precise control over low temperatures. All things, with only a few exceptions, need at least some heat to function since it is almost impossible to move at absolute zero. Letty is one of these exceptions. Letty's combined ability seems pretty much unbeatable, provided that she's willing to use it in battles.