Spring is here and the graduating students are planning a trip to sunny Okinawa. Shizuku and Honoka have invited Miyuki and Tatsuya to a party that sounds like the perfect opportunity to relax for once. It sadly won't be all fun and games because the siblings have also been tasked with stopping a terrorist plot while they're in the south islands. What are the chances? Romance is in the air and danger is on the horizon-this is sure to be a vacation to remember!