Castle of Dreams

The Castle of Dreams (夢の城, Yume no Shiro) is the name given to a dream world created and maintained by Echidna. It is where her soul permanently resided up until her reincarnation as Omega, and where the souls of the other five deceased Witches of Sin currently inhabit.

Information
Although it is known as the Castle of Dreams, the realm is only a castle in name. Echidna can control the world's form at will. It most often appears as a place with blue sky, white clouds, an expanse of green hills, and a place where Echidna holds her tea parties, consisting of a varying number of chairs, a table, and a parasol. However, on one occasion, the Witch of Greed made the world crumble into dust and replaced it with a void of nothing but darkness.

Echidna holds complete and total control over the dream world. She can bring freely bring others into the Castle of Dreams on a single occasion, but it becomes more difficult for her to give the same person multiple invitations. The condition for one to visit her multiple times is the “desire to know”, which must be stronger with each successive visit. She can make others invited into her dream forget that they met her, and in most cases, one cannot awaken from the realm unless Echidna wills it, though it is possible for someone to be awakened from the outside by a separate force. People inside of the dream world only exist as souls, and they are cut off from most factors in the outside world, including time. The flow of time is different between both the real world and the Castle of Dreams; however, the effect on the outside is sparse. Despite being under Echidna's control, the Castle of Dreams is prone to external influence from forces like the Witch of Envy, Satella, who crossed over multiple so-called “boundaries” in order to reach Echidna's dream world.

The other deceased Witches of Sin besides Echidna are also housed within the Castle of Dreams, but they only exist as the vestiges of their souls. The castle was formerly connected to the Witch of Greed's tomb at the Sanctuary until Echidna began possessing Omega's body. Upon successfully gaining a new vessel, she was able to move both it and the souls of the other Witches into a pyroxene crystal. Currently, the other Witches can speak directly into Omega's mind while she is within her body, though she retains the means to enter the Castle of Dreams as Echidna and converse with the souls of her friends.

Residents

 * Echidna
 * Typhon
 * Minerva
 * Daphne
 * Carmilla
 * Sekhmet

Trivia

 * Echidna suggested to Natsuki Subaru that he knew of a space that was similar to her Castle of Dreams. In response, Subaru denied knowing what Echidna was talking about, but he believed that she was not wrong and quickly accepted that he was in a dream world without understanding why.