This study will evaluate the safety and efficacy of Harvoni® (ledipasvir/sofosbuvir (LDV/SOF) fixed-dose combination (FDC)) treatment under real world use in Japan. Among adult patients with chronic genotype 1 hepatitis C virus (HCV) infection and treated with Harvoni in routine clinical use, the primary objective of this study is to evaluate the incidence of adverse drug reactions (ADRs) under real world settings.