In Japanese with English subtitles

The seasons go by, and their second spring is almost upon them... The "irregular" elder brother and his younger sister, who is an academic star, are about to finish their first year at Magic High School. Tatsuya, Miyuki and others have decided to spend their spring break at a certain private villa on Ogasawara Island. They are making the most of their brief vacation. That is until a young girl named Kokoa appears before them. She has escaped from the naval base, and tells Tatsuya her one wish...