Kudoa septempunctata is an important myxozoan parasite in culture and capture fisheries as it causes food poisoning in humans. ​This species is generally considered a parasite of olive flounder Paralichthys olivaceus because K. septempunctata-related food poisoning cases are associated with consumption of raw infected P. olivaceus. ​However, the host range of K. septempunctata remains unclear. ​Moreover, there is scarce information on the lifecycle of the parasite, and this hinders the development of a fundamental prophylactic measure in fish farms. ​During the survey of wild fishes at a K. septempunctata endemic area, kudoid myxospores were detected in the somatic muscle of grass puffer Takifugu alboplumbeus and Japanese whiting, Sillago japonica. ​Our morphological, molecular, and histological analyses identified them as K. septempunctata. ​While the infection levels in T. alboplumbeus were higher (up to 92.3% prevalence) than those in S. japonica (23.8%), the maximum spore density in the muscle tissue was about 7×10⁴/g in both fishes, which is far less than the food poisoning risk value of 1 × 10⁶/g. ​These findings indicate a wide host range of K. septempunctata and further attention is required for its possible infections in fishes other than P. olivaceus.