In the quiet of their shared home, a curious stepsister, barely legal and petite, asks her stepbrother to assess her growing breasts. He hesitates, but her pleading eyes and the sight of her small, perky tits in a tight tank top prove irresistible. He tentatively cups them, feeling their weight and noticing their slight firmness. She moans softly, her nipples hardening at his touch. He grows hard in response, and she notices, biting her lip. "Is it working?" she asks, referring to the growth cream she's been using. He swallows, "Yeah, it's... definitely working."