Strike the Blood, Vol. 11 (light novel‪)‬

WHEN ALLIES BECOME ENEMIES, WHO CAN YOU TRUST?
New Year's Day is right around the corner on Itogami Island, and everyone is getting ready to celebrate! ...Well, almost everyone. Nagisa, off on a trip to the mainland to visit her grandmother, hasn't been returning any calls or texts. Equally troubling is Yukina's sudden and complete loss of contact with the Lion King Agency. When Kojou and Yukina's frantic attempts to find answers reveal evidence of a magical incident, Kojou decides to risk everything and travel to the mainland to find Nagisa himself. But in hismost desperate hour, an unexpected adversary stands in his way...