Takashi ends up living with his new stepsister after his father remarries. At first, he worries it might be awkward living under the same roof with a girl, even if she's only his stepsister. But upon seeing her, he's taken aback - her name is Alice, a beautiful girl from Northern Europe. While part of him is happy to have such a lovely stepsister, her overly large breasts stir confusing emotions within him.

Still, as he watches Alice genuinely trying to adjust and become part of the family, Takashi does his best to suppress any impure thoughts and treats her as a proper older brother should. However, one day, when he accidentally sees her naked, the wall of restraint he's built up comes crashing down...