Strike the Blood: Valkyria no Oukoku-hen

Royal families from the Kingdom of Aldegia and the Warlord's Empire arrive on Itogami Island to renew a mutual nonaggression treaty. Kojou expects Princess La Folia to be occupied with official duties, but instead finds her fleeing through the city and is stunned to discover that the imposing man pursuing her is her father, King Lucas.

The awkward reunion soon gives way to a genuine crisis when terrorists move against the royal gathering. Their demands conceal a plan to disrupt the treaty and assassinate Dimitrie Vatler, forcing Kojou and Yukina into a battle where international politics, vampire power, and La Folia's safety are all at stake.