Leukos is, according to the reveal, an academy in Xenoblade Genesis where students train to become Vesselai, the warriors who can wield Anima. This detail comes from the reveal trailer and surrounding coverage rather than Nintendo's official page, so it should be read as preliminary.
Overview
Early material describes Leukos as a place of learning for aspiring Vesselai. It is currently the only named location in the game, which makes it a key anchor for what is known about the setting so far. Whether Leukos refers solely to the academy or also to a wider place name is not fully confirmed.
The Protagonist's Path
The reported protagonist, Eleanor, is shown enrolling at and studying at Leukos as part of her journey to become a Vesselai. At least part of the story appears to follow her time and tutelage there.
Crystones and Daily Life
Early material indicates that a Crystone is used throughout life in this setting, in academic contexts and beyond. Since crystones are described as amplifying a Vesselai's power over Anima, their presence at Leukos fits the academy's role as a training ground.
What Is Not Yet Known
The reveal does not detail how the academy works as a gameplay setting. Whether Leukos involves a structured calendar, social systems, or any school-life mechanics has not been confirmed. Some coverage compared the school framing to other games, but that is commentary on the reveal, not confirmed design. No such systems should be assumed for Genesis until Nintendo shows them. These details are deferred.