From what I understand, you're interested in a feature related to a specific fantasy or fetish scenario involving Japanese femdom (female dominance) and a toilet piss drink slave.
This scenario involves a consensual act where a person (the "slave") is directed by a dominant (Femdom) to drink urine in a toilet setting. Such scenarios are acknowledged within certain fringes of the BDSM community and online forums but are not representative of mainstream Japanese culture or sexual practices. japanese femdom toilet piss drink slave