Thirty years have passed since the exchange between Earth and a different world began… Tsujizono Itsuya , leading a life of poverty, is suddenly abducted as soon as he returns home from his part-time job, leaving him in a state of disarray about the events that transpired. To his bewilderment, the kidnapper discloses the truth. — It was revealed that Itsuya’s parents sold their own son to repay the debts they had accumulated. In a state of despair, Itsuya finds himself being purchased at a clandestine auction, and the buyer happens to be none other than the daughter of a duke from the other world. The young lady, now his mistress, assures Itsuya that she will provide him with the essentials of life in exchange for fulfilling a particular task. That task is simple. Itsuya must allow the inexperienced vampire maid, Hizuki Sakura, to feed on his blood. Additionally, he must allow the cheerful and carefree succubus maid, Sakiba Lilith, to extract his life force. In other words, he becomes their sustenance. In addition to this unimaginable treatment, what is even more astounding is the fact that both maids, Sakura and Lilith, are none other than Itsuya’s renowned classmates, considered the two most beautiful girls in his high school! Thus begins the intricate tale of a symbiotic existence, where Itsuya becomes the nourishment that sustains the lives of these three individuals!