Many years later, as she becomes a successful businesswoman who teaches in her spare time, she will realise... " Wait, shit, I forgot to start my diet!"
Apparently Japan didn't produce soap (as we know it) before 1870. All soaps were imported. Commercial success for producing soap is also plucked right out of Japan's history.
Why does all isekai think soap as some sort of revolutionary shit. Soap is discovered around 2800 BCE according to Google. Im okay with katanas being best weapon and bathing house as a lucrative buisness but SOAP !?