Sampling using nasopharyngeal swabs, although minimally invasive, can cause pain. Therefore, discomfort should be minimized even when conducting simple, rapid diagnostic tests by enabling multiplex detection from a single specimen. Several companies including TAUNS Laboratories, Inc. (Shizuoka, Japan), the market leader in manufacturing medical rapid test kits in Japan, have developed an immunochromatography test kit for multiplex detection of influenza A and B viruses and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This study aimed to conduct a comparative performance evaluation of the ImunoAce® SARSCoV-2/Flu kit against multiplex detection kits manufactured by four other major companies approved by the Japanese Ministry of Health, Labor, and Welfare and used in medical facilities.