It Isn't Hygiene. It's Chemistry.
Somewhere after midlife the body starts producing more 2-nonenal. It's an oily compound rather than sweat — which is why it settles into skin, clothes and bedding, and why products built for sweat walk straight past it.
What Persimmon Tannin Does
Perfume covers it for an hour or two. Ordinary soap washes the skin and leaves the compound where it is. Kaori follows the Japanese practice of cleansing with persimmon: the tannin binds 2-nonenal during the wash, and what it binds leaves with the water.
Nothing is layered on top, so by the afternoon there's no second smell arguing with your own perfume. Your skin simply feels clean — and you can hug the people you love without second-guessing yourself.