I've Been Killing Slimes for 300 Years and Maxed Out My Level

Falfa woke up in the form of a slime! Of course, that's not too shocking since she's a slime spirit, but her sister Shalsha laments that this has never happened before and she doesn't know how to change her back. So Azusa sets off with Shalsha and Beelzebub in search of an "unusual slime" who might know a way to change Falfa back...