A series of 3-5 minute specials that were bundled with the HighSchool DxD DVD and Blu-rays. They are a stand alone set of episodes that are not a part of any story line in particular.
Special 1: We're Going Sun Bathing!
Special 2: Akeno-Senpai's Private Training!
Special 3: A Little Bold, Koneko-Chan... Nyan!
Special 4: The Untold Story of The Dress ...