A little late here, but the black and white flashback at the beginning took place during the Edo Period (1600-1868) while the story takes place in the Taisho Period (1912-1926). The implication is that this demon has existed in the Entertainment District since then, probably reappearing at intervals so that people don't realize it's the same one. Also, Muzan appeared to her shortly before Zenitsu and the others even got to the entertainment district.
They don't go into too much detail here, but Oiran, despite being prostitutes, are actually considers to be entertainers first and foremost. While the draw for lower ranking prostitutes is obviously sex, Oiran rise through the ranks thanks to their intellect and talents at the traditional Japanese arts such as painting, flower arrangement, dancing, playing one or more instruments, or performing traditional Japanese tea ceremonies. Their services were only available to the wealthiest of patrons, with whom the Oiran were expected to be able to match wits and intellect. The rank actually earned the nickname "keisei" or "castle toppler" for their perceived ability to win over the hearts of upper-class men.
Iridescent
2022-01-06 17:05:26 +0000 UTC
Daki is using the paper to take off the excess lipstick so it wont smear lol just common woman tings xD