On the first day after the summer vacation, a pilot from the Great Zogilia Republic who went back to the past due to an accident attacked Watase Aoba. In order to protect Watase Aoba, Yumihara Hina also boarded her own machine and fought the enemy. But in the end, the two of them came to the future world due to another accident. During the transfer process, Yumihara Hina only left a message "Dio is waiting for you" and then disappeared...