Read Be My Love, My Lord Manga:
This is a world where humans keep beasts and beasts obey humans. Born as the second son of a well-known family, the lonely Reiji has always had his beastman servant, Tsubaki, as irreplaceable presence since he was a child.
But once day his feelings turn to love, and Reiji playfully kisses Tsubaki, which invites his bestial lust. His sharp bite overflows with his own repressed feelings, but comes wi more.. th a dark realization; they are different races, different castes. Can they overcome these hurdles and embrace their love?