​Newlywed archaeologist Akira’s father leaves him with his new stepmother and three stepsisters, Yuki, Nana, and Miu, while he embarks on a honeymoon. Unexpectedly, Akira’s father discovers a significant archaeological artifact, compelling him to remain on-site. Left alone with his attractive stepfamily, Akira’s life takes an unusual turn when he is caught in an intimate encounter with his stepmother, Yukie. Intrigued, he stumbles upon a mysterious box containing a sacred scroll and three enchanted bottles. As he unleashes his father’s teachings and deciphers the ancient Sumerian script from the scroll, Akira unwittingly forms a mystical pact with the goddess Inana. In order to avert impending doom, he must gather the love essence from his sisters before the upcoming full moon.​