Today on the Twitter account for Fujino Oomori’s DanMachi light novel series it was announced that a new OVA will be released for it on December 7th. The OVA will have both a DVD and Blu-ray release with a single episode, a CD with the ED sung by Hestia, newly recorded audio commentary, creditless ED and 8 page booklet will also be included. It should also be noted that the Blu-ray Disc box of the light novels anime series is set for release on the same date and will also include the OVA. The light novel series is also currently being published and released in North America by Yen Press.
The series which released between April 4th 2015 and ended June 27th 2015 with 13 episodes is based off of its light novel series that began on January 15th 2013 and is still currently ongoing. A manga would later start for the series on August 2nd 2013 and is also currently ongoing. There is another anime series which is also set for released titled DanMachi: Sword of Oratoria, however no release date is confirmed for it yet, the OVA however will be focusing on Aiz Wallenstein. Finally is a plot summary of the series below quoted from MAL:
Commonly known as the “Dungeon”, the city of Orario possesses a huge labyrinth in the underground. Its strange name attracts excitement, illusions of honor, and hopes of romance with a pretty girl. In this city of dreams and desires, new adventurer Bell Cranel has his fateful encounter with the tiny Goddess Hestia.
Thus begins the story of a boy striving to become the best adventurer and a lonely goddess searching for followers both working together to fulfill their goals.