Three stories set after the &quot;Kageri Saku Senkō&quot; event of the Senki Zesshou Symphogear XD Unilimited smartphone game, in which <spoiler>Miku travels to a parallel world and helps its version of Hibiki, referred to as &quot;Grey Bikki&quot; or &quot;Edge Bikki&quot;, who didn't have her version of Miku to mentally support her following the Zweiwing incident, in order to save her own Hibiki, whose soul was linked with Grey Bikki.</spoiler>