Darker than Black: Kuro no Keiyakusha Gaiden  

Darker than Black: Ryuusei no Gemini Specials, Darker than BLACK 2 OVA, Darker than Black: Ryuusei no Gemini Episode 12, Darker Than Black: Gemini of the Meteor OVAs, Darker than BLACK -黒の契約者 外伝, DARKER THAN BLACK: Kuro no Keiyakusha - Gaiden, Darker than BLACK: Origin

After escaping from Hells Gate's repercussions, superpowered Contractor Hei and his friend Yin seek refuge at a peaceful inn by posing as a married couple. To recover from recent events, Hei tries to make friends with the other guests. However, he discovers that one of them is another Contractor assigned to kill him. This encounter ends in tragedy for both Hei and Yin as they must fight for their lives while also dealing with emotional wounds from their past together.