An unmanned bipedal AC reassembled using classified means <spoiler>by [[allmind (armored core 6)|ALLMIND]]</spoilers>, the new designation 'Echo' is without a serial code, though its made up parts produced by the Rubicon Research Institute under the serial code IA-C01X 'Ephemera'. Despite being developed half a century prior, like all Institute developed machines, it is able to keep up and exceed modern weapons in many aspects thanks to it's Coral-powered technology. The AC Echo has an alien but yet feminine appearance, it is painted entirely in black, silver and pink.

<spoilers>Echo is first encountered as an enemy unit around the mid chapters of the game simply under the designation 'Institute AC', painted entirely in silver with red arm units.</spoilers>

<spoilers>Though designed to be unmanned, when it's reassembled into the Echo, it was piloted by [[ayre (armored core 6)|Ayre]] in the story route 'Alea Iacta Est' to assist the player character in the final mission.</spoilers>
echo (armored core 6)