Kawasaki disease (KD) is an acute childhood vasculitis that may cause late coronary complications. We report a 25-year-old man with childhood KD who presented with acute coronary syndrome without conventional cardiovascular risk factors. High-sensitivity troponin T was elevated, and transthoracic echocardiography showed regional wall motion abnormalities with reduced left ventricular ejection fraction. Coronary angiography revealed subtotal ostial left anterior descending artery stenosis with a giant aneurysm and a giant right coronary artery aneurysm. The heart team decided to proceed with coronary artery bypass grafting. Clinicians should consider late KD-related sequelae in young adults with acute coronary syndrome.