Kuro Ai: Hitoyozumakan Inkou Rannyuuroku
English title: Dark Love
Japanese title: 黒愛 一夜妻館・淫口乱乳録
Alternative titles: Kuro Ai
Type: OVA
Source: Visual novel
Episodes: 2
Status: Finished Airing
Aired: Apr 29, 2005 to Jun 24, 2005
Duration: 26 min per ep
Rating: Rx - Hentai
Studios: Shinkuukan
Producers: Green Bunny
Licensors: Media Blasters, Kitty Media
Genres: Hentai

Tetsuya's investigation into a luxurious hotel turns over a nest of yakuza and a bizarre orgy cult. On rich silk sheets and velvet chairs, the rich and powerful participate in sex acts so depraved that just witnessing them is likely to turn a man into a monster. But the true purpose of this cult is a pact with evil energies that can literally turn Tetsuya into an inhuman demon. 

(Source: ANN)