A Review of Darker Than BLACK: Kuro no Keiyakusha Special: Exactly what it sounds like, this is simply an extra episode that fits in as an OVA for season one. however, just because it is an OVA doesn't mean it's not worth your time. If you enjoyed the difference and variety of the various mini-arcs of Darker Than BLACK, then I definitely believe this will sit well with you. With another decent story, some good action scenes, and a bit of comedy, not mention the (as always) stellar animation and sound design, this extra episode easily fits in with he Darker Than BLACK franchise. And that's whyDarker Than BLACK: Kuro no Keiyakusha Special gets a 7/10