"You still didn't tell me; would I be like dark beings now? And what's the deal with the cursed blood depletion? Why isn't my heart making any more blood?!"
In reply, Immortika wrote, "Hah, you still don't get it, do you? The Dark Beings are completely different from the living beings. They don't have a life force, and that's why they need to plunder it from living beings.
"But you are not a dark being; it's just that, in a sense, you are discarding your outer shell that is no longer required. You'll still be considered a living being but with a different appearance. This is the Body Transformation.
"Besides, didn't I say you'll reconstruct your body from scratch? Just think of it as living naked for a while until you get befitting clothing for yourself.