After reading the story... it's really surprising to heard them used as sexual lubricant.
The Miss in that story gave them to a hatless KoMarisa.
Marisa's mother is killed by another human and she escaped before her own father killed her sister Reimu for having no accessories (the abyuser took their hat).
The juice is sweet, but with yukkuri's messy eating, it smeared her body and causing great deal of itch.
When a pair of Marisa and Patchouli came to punish the uneasy yukkuri, KoMarisa is already scratching her body to the ground, and finally to a sharp stone without realizing pain or how her skin is torn in the process until she dies.
Patchouli alredy vomitted cream and died of shock, while Marisa still didn't realize her body is also smeared in the yam juice from when she body slammed the KoMarisa into the feeding bowl.