I felt it was a bit weird not for her to have such an ability but to claim she had never used it seeing as from what i know of the myth it's pretty much the succubus main ability. Also, I can possibly see Kurumu arriving in the middle of it and interrupting the whole flashback postponing the answers to all of Ryll's questions a bit longer

Alucard... not the most original name for a vampire but it works, and that monstrous figure seems like something Akua would take in order to fulfill her goals

But damn this whole chapter was a surprise after another, THIS is how you make a monthly series.