Saiki Takaya, a man who is easily misunderstood, one day discovers a flask containing the succubus Lilim. She is very attractive, but she also has a tendency to drain people's life force. She literally surprises the life out of him when she kisses him unconscious. Lilim turns out to be a succubus who gains energy by kissing men. Lilim then flies off in search of more "food," but returns later, stating that Takaya's life energy was the "tastiest." From then on, Takaya's parents accept Lilim as a live-in girlfriend of sorts, and Takaya's heart seems to start wavering toward this voluptuous devil.