|Game||Tales of Xillia|
•Milla Maxwell (currently)
The Spirit Realm is an alternate dimension to that of the human world, and as such, it bears a near-identical resemblance to it despite being veiled in a surreal atmosphere.
As evidenced by interactions of Milla and the Four with the denizens of the Spirit Realm, it has its own populace, likely parts of people who underwent Maxwell's soul purification process who are treated as spirits in this realm.
When humans channel spirits in their realm, the spirits receives humans' mana and then use it to perform spirit artes in human realm.
Sometimes events from human realm manifest as mere projections of what is happening in the "outside world", but the two realms cannot interact with one another.
Milla Maxwell's soul is taken to be reborn like all other humans, but the Four Great Spirits intervene due to how close they became in the last twenty years and bring her to the Spirit Realm. The Milla they rescue, however, is nothing but a shell at this point, lacking both personality and memories. The Four Great Spirits realize that their lives are now forfeit because they have disobeyed the true Maxwell, so they decide to travel with Milla as she wanders into familiar landscapes, including Hamil and the Aladhi Seahaven, and discovers that she is being hunted for the sin of false reincarnation. At the Seahaven, Milla dreams of Jude Mathis and is told the truth of what the Four Great Spirits did, so she returns Nia Khera, where they are confronted by the Great Spirit Muzét.
The Four Great Spirits give themselves up to be reincarnated while telling Milla that she is now free to be anyone without being bound by the name "Milla Maxwell". She is unable to let it go and follows them to her shrine, where she confronts and defeats Muzét after the Four declare their allegiance to Milla as opposed to Maxwell. They then obtain a light orb that contains Milla's memories, which they use on the Nia Khera Hallowmont. There, Milla witnesses Jude and the group's struggle against Maxwell in the Temporal Crossroads and incarnates herself in a physical body, helping to first break Maxwell's barrier and then defeat him.