Minami's father, a former mercenary, is invited to a party held by the American navy, and Ren and his friends go along with him to Okinawa for their summer break. On the beach, Ren runs into a mysterious girl who asks him for help and then vanishes. Ren can't stop thinking about her plea, so he sets out to save her and learn the truth about who she is. The one-episode ONA special mixes action and fantasy as her identity gradually comes to light.