ONU judges ultrasound scan quality while the scan is still happening, so a lay user at home can produce clinician-reviewable breast images without operator training. Five-year relative survival falls from 100% for localized breast cancer to 33.8% once disease is distant, yet routine screening is easy to postpone. A circular smart-mirror display, a wireless linear-array probe, and a charging dock guide preparation, probe positioning, scan direction, and progress through visual and voice prompts. Ultrasound, motion, contact, and position data are synchronized to evaluate handling stability, image quality, and scan coverage during use. When incomplete areas are identified, the mirror guides location-specific rescanning before the session ends. Powder-room placement links gel application to cleanup, and modular architecture supports component-level replacement. ONU extends breast-health management from isolated clinical visits to repeatable home participation while preserving mammography, professional interpretation, and diagnosis.