they both can! but i think the small master didn’t do it because he can’t remember how to do it? he can only remember it if his hair turned white because that’s literally his original self and not pretending/want to be someone/human and remember that girl btch? small master can’t remember her because he already toss aside his past memories so he tossed them aside like any other girl he had relationship in the past and find another plaything to satisfy his desire to become human even though it can’t satisfy himself because it’s all pretending to be a human and those blood stones we saw is his, everyone of them signifies his past relationships to satisfy his desire to feel the emotions, and to become a human.
Was it ever explained why small master's blood was able to turn the hunter into a vampire, but couldn't turn the chairman?