"A potent drug.
It is hard to detect and it will even fell an elephant."
The Sleeping Drug is an item found in Prisoners of the Elder One. There are two ways to get it: from Gillermo after using the Hellfire Wand on Satsu, or from collaring Satsu (keep in mind that this makes the Sleeping Drug unusable, as it requires the Collar). It can be used with Tofu and served to Yuki to put her to sleep and save Tiffany. It can also spike the Cake, but sedatives do not work on demons, and Yuki doesn't like sweets.