A 38‐year‐old man was stung on his left shank and knee by a jellyfish; he found some jellyfish tentacles around him. The species of this jellyfish was likely to be Cyanea nozakii Kishinouye based on the record of distribution of jellyfish and observation of jellyfish in the area at the time. Within a few minutes, the affected areas became swollen and red (a). He was given antihistamines (loratadine, 10 mg, once daily for the first 3 days) and an anti‐inflammatory (topical Bactroban cream, three times daily). Approximately 5 h later, the affected areas became dark red (b) and occasionally he felt itching and pain. Ten days later, dark red scabs appeared on the affected areas (c). White scabs appeared on the affected areas (d) 25 days later, and he felt pain because of the seamed white scabs. He smeared the Bactroban cream on the white scabs to relieve the pain and the white scabs became dark red (e). Four and a half months later, dark red marks were still left on the affected areas (f). This is a rare and severe case of jellyfish stings.