This is acutely something I have been wondering about since the substance was first introduced in this series.
My personal theory is that it works by the person that is holding its own definition.
So if the person that is holding it still thinks of themselves as virgin then they are and they get a positive reaction, if they don't believe that they are they will get a negative reaction. This might also explain the wide range of effects that we have seen so far from the substance.
Thanks everyone at
Mangazuki for the translation