On a second read I noticed how naturally smooth Shamiko is. She is obviously not aware of it but I guess she is not a succubus for nothing.
It's a classic playbook move to first lower the expectations and then make a surprise, to maximize the effect. It may fail horribly when it's obvious but Shamiko did it perfectly, thanks to it being unintended (consciously at least).
@thofheinz - I think it's more of a "tag", akin to a necklace. It still does mark her as Shamiko's.