A recent blog
revealed that the seventh manga volume of Witch Craft Works
will bundle a DVD on July 7, 2014.
The OVA will be 25 minutes long.
Source: Witch Craft Works blog
Story by Stark700
Witch Craft Works OVA
Update April 28
According Afternoon magazine, the OVA has been delayed. It will be bundled in volume 8 instead of volume 7. The new release date will be announced soon.
Update July 7
According to Natalie, volume 8, which bundles the OVA, will be released on January 7, 2015.
Discussion continues from here.