How to Warm Up a Cocytus 2K

It's been a month since Eri's first dive into the Chamber of the Demon Lord and she's gotten pretty used to her new life. She learns that whatever the beast is, it can take on any form—from primordial creatures to fat, middle-aged men. As their next mission starts, a building has formed, and while Eri makes her way into the structure, Maruka is taken away. Inside, the cold hands of a masked man in a cloak touch Eri's hot body. Is this the true form of the Demon Lord?