Rimuru and the Class S students have made it through the first exercise of the Freedom Academy's annual outdoor training event. Class S has arrived first at the destination, the mansion of Count Guratol, and now they're ready to begin the second exercise, a cave exploration... but awaiting them there are thieves who hope to kidnap the students and make a fortune returning them for ransom money. Just when it seems like Rimuru's students have fought them off thanks to the skills he taught them, they realize a monster is lurking among the thieves! This is the final installment in the brand new episode created by the original author, Fuse-sensei, just for this OAD release!