House of Lamentation

Located in the Devildom, The House of Lamentation is a huge mansion where the seven demon brothers Lucifer, Mammon, Leviathan, Satan, Asmodeus, Beelzebub, and Belphegor live. After the beginning of the Exchange Program, MC lives with them. They all have individual rooms, except for Beelzebub and Belphegor who share a room.

Background
The mansion was originally built in the human world on the outskirts of a village. The people who previously lived there were a married couple with their seven children, and their servant.

One day a terrible tragedy struck inside the house. Every family member was brutally murdered in a different way, in a different room, and the servant had hung himself in his own room. The only survivor was the oldest son, who claimed the servant committed the crimes. The authorities deemed the case closed, but rumors started spreading that the oldest son was on bad terms with his family. It was then believed that the servant tried to stop him but was killed and framed to be the scapegoat for the murders. The son continued living in the house until he died of old age.

Afterward, there were figures seen in the windows, and screaming and arguing could be heard despite being vacant. Because of the dark history, the mansion became known as the "House of Lamentation".

Eventually, the mansion was transported in the Devildom and became a dorm for the brothers.

Trivia

 * Lilith's room was from the Celestial Realm and likely added by Lucifer after he and the brothers moved in, for Beelzebub had no knowledge of its existence.
 * According to the dollhouse model, her room is adjacent to Lucifer's.
 * The attic was considered Lucifer's private sanctuary where he kept things from the Celestial Realm, perhaps even Lilith's things. Lucifer went to great lengths to keep his brothers away from it, including casting a spell that prevented them from entering it, but it doesn't work on humans and angels.
 * There are seven headstones in the front yard.
 * The architecture looks to be a Gothic Revival.
 * MC's room is stated to be on the other side of the kitchen, as confirmed in Lesson 5-2 when Beelzebub destroyed a section of the kitchen wall which was also part of MC's bedroom.
 * Their room may also have their own bathroom for Beelzebub stated that Mammon often left his toothbrush, as well as his phone charger, in their room.
 * Their room was likely the servant’s former room since it was smaller and right by the kitchen.
 * In the underground tomb, there's an effigy of Lilith with her holding the brothers' grimoire. After the events with Luke and Beelzebub, Lucifer had Cerberus patrol the area to guard the grimoire.
 * There's at least one tree within the house for there's one in the MC's room and seen in the hallway. It's unknown if it's the same tree.
 * The laundry room is never shown, but is by the kitchen as confirmed in a chat where Leviathan accidently flooded the laundry room which extended to the kitchen.