After a string of personal failures leaves him depressed, Shougo is targeted by Tiffany, a highborn succubus drawn to the bittersweet taste of his heartbreak. Discovering that Shougo is an exceptionally high-yield source of energy, Tiffany forces him into a pact to become her servant. Now bound to her will, Shougo must provide his life force to sustain her magic in a provocative and chaotic new living arrangement.
After Tiffany introduces her familiar and sister, Chloe, Shougo is left alone with the hostile half-demon. Despite Chloe's insistence that he is merely sustenance, Shougo's empathy for her tragic past leads to an intimate encounter that bridges the gap between them. As Chloe finds solace in Shougo's kindness, the two form a secret pact before Tiffany returns to demand her own meal.