Why regular soap can't fix this.
Regular soap is built to lift away things that dissolve in water — sweat, oil, everyday grime. 2-Nonenal doesn't behave that way. It's fat-soluble, so it doesn't rinse cleanly away. You shower, you feel clean, but a thin residue can remain — ready to release its odor again the moment your skin warms up.
Persimmon tannins work differently. They bind directly to the compound itself — not covering it with fragrance, but neutralizing it. That's the mechanism behind every bar of NONALYS.