Takashi ends up living with his stepsister due to his parent's remarriage. He thought it would be awkward to live with a girl, even if she was his stepsister, but he was surprised when he saw her. Her name is Alice, and she is a beautiful girl from Northern Europe. While he is happy to have a beautiful stepsister, her overly large breasts disturb Takashi's feelings. However, seeing Alice trying to fit in with the family, Takashi suppresses his wicked thoughts and treats her as a stepsister. But one day, Takashi sees Alice naked, and the wall of his reason collapses.