Shinjūkyō (神獣鏡) is an ancient type of round bronze mirror decorated with images of gods and animals from Chinese mythology. The obverse side has a polished mirror and the reverse has relief representations of legendary Chinese shen (神 "spirit; god"), Xian (仙 "transcendent; immortal"), and legendary creatures. (from Wikipedia)
A fragment of a mirror relic that Finé left in the care of the US Government. Using mechanical methods that were derived from the Symphogear system they were able to equip it to their large scale helicopter the "Air Carrier." Like all mirrors, it's special properties are based on its ability to reflect light. One of those properties, "Wizardry Stealth" can not only make the helicopter invisible but also give off oscillations that cut off its signal from any enemy monitoring equipment. In ancient times the mirror was said to have the properties of driving away curses and purifying bad luck. As a mirror, its most potent and basic ability is projecting a brilliant radiance and reflecting back an "ideal form." The mirror's most important role is releasing the sealed Frontier that lies in the middle of the ocean. However that is not an easy task, as mechanically amplifying its power is an imperfect implementation of the relic and has already been confirmed not to work. Although, Miku activates it, it was destroyed along with Hibiki's Gungnir Fragments in their battle.
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