Outcomes with prasugrel single antiplatelet therapy (SAPT) vs. dual antiplatelet therapy (DAPT) in Japanese percutaneous coronary intervention (PCI) patients with high bleeding risk (HBR) are currently unknown.Methods and Results:Data from 1,173 SAPT and 2,535 DAPT patients from the PENDULUM mono and PENDULUM registry studies (respective median DAPT durations: 108 vs. 312 days) were compared. The adjusted cumulative incidence of Bleeding Academic Research Consortium (BARC) 2, 3, or 5 bleeding from 1 to 12 months after PCI (primary endpoint) was 2.8% (95% confidence interval [CI], 1.9-4.2) and 4.1% (95% CI, 3.3-5.1), respectively (hazard ratio [HR], 0.69; 95% CI, 0.45-1.06; P=0.090). The adjusted cumulative incidences of BARC 2, 3, or 5 bleeding from 0 to 12 months after PCI (secondary endpoint) were 3.8% (95% CI, 2.7-5.3) and 5.6% (95% CI, 4.7-6.7), respectively (HR, 0.68; 95% CI, 0.47-0.98; P=0.039). There was no significant difference in major adverse cardiac and cerebrovascular events (MACCE) from 1 to 12 months after PCI (HR, 0.93; 95% CI, 0.63-1.37; P=0.696) and at 12 months after PCI (HR, 0.85; 95% CI, 0.61-1.19; P=0.348) between the groups. Prasugrel SAPT may reduce BARC 2, 3, or 5 bleeding, without increasing MACCE, in Japanese patients with HBR.