According to Comic Natalie, an OVA of manga Vassalord
was announced to be released on March 15th 2013. It will be bundled with the final seventh volume of the manga.
Vasslord OVA official website
Director: Nakazawa Kazuto
Character Design: Takahashi Nariyuki ("Wellber no Monogatari: Sisters of Wellber
Production Studio: Production I.G
The OVA will be based on the first section "Yukyu no Heriogavals".
Source: Comic Natalie