OVA with subs can be found on BSS’s website
Since when were Hei and Yin banging
From ANN:
The official website for the Darker Than Black: Ryūsei no Gemini television anime series has begun streaming a promotional video for the first Darker than BLACK – Kuro no Keiyakusha side story. The side stories recount what happens to the main character Hei in the two years between the original Darker than BLACK – Kuro no Keiyakusha science-fiction adventure series and the ongoing Darker Than Black: Ryūsei no Gemini sequel. The side story videos will be bundled with the even-numbered Blu-ray Disc and DVD volumes of Darker Than Black: Ryūsei no Gemini. (The second BD and DVD volumes will ship on January 27 in Japan.)
WACOCA: People, Life, Style.