Terra Nullius

' Terra Nullius(テラ・ヌルウス; Tera nuruusu, from latin; "Nobody's land") is an island located around the Welsh Coast and is Elizabeth White's temporary and in-and-out training ground and meditation site, where she also takes her apprentice Takumi Higurashi around the events of Volume 3 in DxD: Twice Critical'.

Terra Nullius, has its given name implies, is an isolated area free from all forms of influence, be human or magical, due to its plain condition, harsh and unpredictable weather and lack of humans in the first place.

Appearance
Terra Nullius is a fairly large insland located around the welsh Coast with the shape of a crescent moon. The vegetation there is fairly plain as a meadow and vegetation is limited to simple grass, trees, lily pads, onion-like plants, berries, shrubs, flowers, and other herbs, plus Elizabeth's own coca plantation. Small animal life can also be found such as butterflies, bees and small aquatic lifeform such as shelled animals and jellyfish. At the center of the isle there is a beach that covers all the inner parts of it, and by the coast a small cave where Elizabeth practices shooting.

Terra Nullius is completely absent of human, divine or devil nature since the lack of humans there in the first place makes any form of magical, divine or devil influence be  downgraded to a bare minimum, not to mention that, according to Vali Lucifer, the land 'lacks any form of magical aura' in the air, making it difficult for angels, devils or even Gods to form a connection to it. As for humans, Terra Nullius has an extremely thin air, Elizabeth comparing it too Mt. Everest's peak, the vegetation is unusable for any kind of plantation except its own and the weather is deceiving and unpredictable, as while the land looks green and bright, the breeze around it is shatterly cold even during the day, and if no maintainance is given, the frozen water inside Terra Nullius' pond can stay frozen during even summer. Not even Elizabeth, who's trained there for years, can stay more than a single day in it without succumbing to exhaustion.

Elizabeth discovered, or at least rediscovered the island in one of her expeditions as a mission from the Lucifer Magical Association, and it became her favorite site for training and meditation since nobody would claim or even visit the land regularly and the harsh enviroument and weather were perfect for her training regimen.

Avalon
Avalon(アバロン; Abaron) is Elizabeth's own meditation site in the shape of a chapel located at the heart of the island. A rather impressive construction Elizabeth build herself out of boredom and training, it became Terra Nullius' trademark and meeting point, serving also as a shelter in order for her to introduce the island for newcomers without them succubing to the land's harsh weather.