Ley lines (龍脈 (レイラインス), Rei Rainsu, Japanese for "Dragon Pulse") are a Magic Phenomenon that exist naturally within Earth Land. They are a virtually untapped, raw source of magical power that has filtered through the depths of the earth for years on end that have only recently been discovered and made to use by Esoterologists, their knowledge being limited almost exclusively to the Magic Council and associated divisions.
The Ethernano that exists across Earth Land, and the power that conventional Mages draw from it are primarily found in the atmosphere. The power that exists in the atmosphere can only be endlessly made use of primarily because it is constantly recycled. Those who use Magic unintentionally grant the world their own power once again, which seeps into the atmosphere and, along with the world's natural cycles, becomes renewed and usable once again. As such, Ethernano and Mages exist in a symbiotic, harmonious relationship. Of course, devices such as Face exist to interrupt this relationship and cause near-permanent damage to the entire world.
This is where Ley lines come into play. Unlike the conventional source of Ethernano found in the atmosphere, Ley lines are an alternative pathway taken by Ethernano released and recycled into the world. Rather than transform through the trees, clouds and other natural phenomena, Ley lines are the product of existing Ethernano seeping into the ground and undergoing various filtration processes before becoming a part of a vast network of Ethernano channels that allow for the world to retain its natural beauty.
While nearly impossible to access conventionally, those species who are highly sensitive to the flow of Magic, such as Dragons, are capable of wresting control over such incredible reserves should they be near an appropriate source. Recently, the Magic Council have shown that, through integrating one's clothing with Lacrima, ones sensitivity and ability to absorb external Ethernano is vastly increased, thus their first discovery of such Ethernano channels. From herein, specific Lacrima known as Ethersynthetic Lacrima (魔法合成の魔水晶 (エーテルシンセシチク・ラクリマ), Ēterushinsechiku Rakurima; Japanese for "Magic Synthesizing Spirit Water Crystal") were created and given to specific operatives in order to test the potency of this newfound energy source.