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.