Mahouka Koukou no Rettousei - Nankai Soujou-hen

Spring is here, and the graduating seniors of First High are planning a getaway to sunny Okinawa. At the same time, Tatsuya and Miyuki will be on the island as the Yotsuba family’s representatives at a memorial service for the victims of the invasion there several years earlier. Of course, this is just a cover for their true purpose: foiling a terrorist plot hatched by some deserters and Australian operatives. Their primary target is a party that Shizuku and Honoka will be attending. What are the chances? Romance is in the air, and danger is on the horizon, making this a vacation they’ll never forget!

Adaptation of Light Novel 20.