I know that Muzan is a shapeshifter, and can change his biology and and appearance at will, but why did he specifically choose to turn into a woman? What was the reason for that?
if i'm not mistaken, the reason why muzan shape-shift is to hide his real identity or his face from the demon slayers. I think this is also the reason why the pillars were shocked when oyakata-sama revealed that tanjiro had a brief encounter with muzan.