Hypermucoviscous Klebsiella pneumoniae (hmKP) is a bacterium known to cause lesions, including abscesses, in various organs. Unlike typical Klebsiella pneumoniae, hmKP can yield a positive string test in culture specimens. Infections caused by hmKP often become severe and are associated with a poor prognosis. In this report, we describe a case of iliopsoas abscess, spondylodiscitis, septic pulmonary embolism, and symmetrical peripheral gangrene (SPG) caused by hmKP. The patient received non-invasive positive-pressure ventilation, hemodialysis, platelet transfusions, fresh frozen plasma, thrombomodulin, and intensive antibiotic therapy including rifampicin. The patient underwent 148 days of antibiotic therapy and achieved a good outcome.