IS: Infinite Stratos 2 – Hitonatsu no Omoide
Watch IS: Infinite Stratos 2 – Hitonatsu no Omoide full episodes online English sub. Othes tiles Synonyms: IS: Infinite Stratos 2 Long Vacation Edition – The Memories of One Summer
Synopsis: An extended version of the second season’s first episode, which is under the same title
More info: Myanimelist, Wikipedia