Imouto Jiru(2003)

Imouto Jiru is an adult anime series that follows Akira, whose father remarries and leaves him alone with a new stepmother and three stepsisters while pursuing an archeological expedition. After an unexpected encounter with his stepmother, Akira discovers an ancient scroll written in Sumarian—a contract binding him to the goddess Inana. He learns he must collect the "love juices" of his three sisters in enchanted bottles before the next full moon, or face unspecified supernatural consequences. The series blends fantasy elements with mature themes as Akira navigates his bizarre predicament and complicated relationships with his new family members.