Shido Itsuka goes on sealing Spirits' destructive powers by winning their affection, and his next problem is the Yamai twins. Kaguya and Yuzuru are one Spirit split into two rival bodies, locked in an endless duel over which of them is the real Yamai. Choosing one means rejecting the other, and Ratatoskr has no plan for that. Meanwhile the anti-Spirit organization DEM Industries escalates its operations under the ruthless Isaac Westcott.