Yuzuki's father remarried, and his older daughter, Arisu, came to live as Yuzuki's stepsister. Having lost her mother at an early age and lived alone with her father, Yuzuki felt confused by the sudden appearance of her new stepsister, yet gradually found herself drawn to Arisu's warmth and charm. Arisu is a lesbian who had long awaited the chance to live together with Yuzuki. What she desired most was to embrace Yuzuki, who was as lovely and innocent as a doll. That longing quickly began to come true.