This chapter outlines the unique history and complications of breast augmentation using injectable materials in Japan. Despite early prohibitions in the West, this practice persisted in Japan from the 1950s to 1970s, leading to widespread complications. Materials such as paraffin, silicone, and unregulated substances like “Organogen” were used, causing deformities, granulomas, and in some cases, autoimmune-like syndromes termed “human adjuvant disease.” Patients often presented years later with severe symptoms. Imaging modalities like mammography, computed tomography (CT), and magnetic resonance imaging (MRI) aid in identifying these materials preoperatively. Surgical treatment typically involves excision and, in some cases, autologous tissue reconstruction. The authors emphasize that the historical failures of injectable augmentation should serve as a cautionary lesson in the context of newer materials like bioabsorbable gels.