Here's where the hell starts: 25 chapters of constant death, torture, and unspeakable horrors by the Witch Cult.
Subaru and Rem are tortured, mutilated, and killed by Betelgeuse, the Bishop of Sloth.
In one of the loops Subaru finds his way back to the mansion alone, only to find the whole village piled in a mountain of corpses, Ram mutilated in front of them, Emilia dead in the mansion, and an enraged Puck going out of control, freezing the entire region and instantly killing Subaru.
In another loop Subaru is driven insane from the torture he receives from Betelgeuse, who rips apart Rem in front of his eyes piece by piece.
This insanity lasts a whole loop as Rem tries to carry Subaru who has turned into a drooling madman and make back to the mansion. At the end of this loop, the two are again captured and tortured, but this manages to snap Subaru back to sanity thanks to his anger.