What's with the pattern on the nape/upper back of the giesha at the start of the chapter? Idk what it's supposed to be
I can't confirm if that is how it is in real life... but, Geisha do use a particular makeup that makes their faces really white, and they put it all the way around their nape.
I can't say if that "pattern" is something they do, or if this was just the author's "artistic license" to make things a little dramatic and impactful, but I can say that it at least alludes to their official makeup.