IS: Infinite Stratos 2 - Hitonatsu no Omoide IS: Infinite Stratos 2 Long Vacation Edition - The Memories of One Summer
This extended version of the first episode rings in the start of Infinite Stratos 2. When Ichika gets invited by Laura to an amusement park, he has no idea that he wasn't supposed to invite the other girls! Meanwhile, as the tumultuous "date" continues, a mysterious woman named M breaks into a guarded facility to claim powerful IS.
[Source: Sentai Filmworks]