While assaulting a Shuuki nest, the 7th Squad are confronted by a mysterious girl riding atop Unihorn, Kyoukaβs sworn enemy. Who is she, and why does she seem to recognize Yuuki? Thereβs no time to ponder that mystery, however, as the leaders of the 6th Squadβincluding Himariβs sisterβ arrive for joint training! The stage is set for a grudge match between the two siblings, and Himari drafts the Squadβs slave-cum-caretaker to help. Not that Yuukiβs complainingβmore masters means more sweet rewards!