Kana lived with her sister Shio and Shio's husband Keita. Originally, she had been living alone with Shio, but after they got married, Keita moved in. She wasn't angry about it; rather, she was secretly happy to have a cute younger brother. One day, Kana returned home late from work and dozed off on the last train. She felt a gaze from the opposite seat and slightly opened her eyes to see Keita intently staring at her lower body while jerking off. Shocked, Kana also felt a perverted urge rising within her and began lifting her skirt to expose her panties.
