Entremets is the name of the Central Basilicom in Lowee in Hyperdimension Neptunia and Hyperdimension Neptunia Re;Birth1. The Central Basilicom, is where all local Basilicoms are managed and where research regarding the monsters in Gamundustri is preformed. The CPU of Lowee also resides there when she descends down from Celestia to visit the human world.
The Central Basilicom is guarded by a large snowy forest to deter travelers from coming to visit due to its less than welcoming location. Each Lowee Basilicom, including the one in Guild City, is connected to Entremets via secret underground pathways.
Entremets is where Neptune first speaks with Blanc, albeit not in person, on her journey to find the Lowee Key Fragment. She is rudely shunned away by her and the girls receive help from her Chamberlain, Financier, instead.
The girls end up going to visit Blanc a second time by using one of the underground pathways in Guild City. Neptune asks for information regarding monsters and the Key Fragment once again, and Blanc immediately speaks back to her in a rude manner. However, in the middle of the conversation, she becomes suspiciously nice after hearing Neptune call her by her full name. This is due to Blanc finally understanding that Neptune really has lost her memories.
During the Guild raid of the Central Basilicom, Neptune and the others use the underground pathways to help Blanc escape against her will as monsters are unleashed inside of her Basilicom.
Hyperdimension Neptunia Re;Birth1