On February 23 in the 4th year of Temmei (1784), two farmers were reinforcing ditches for the rice paddy and found a large stone. They pried it out with an iron lever and saw something glittering. The farmers picked it up and rinsed it in water. It looked like a fine seal. So they took it to Jimbei, a farmer and the owner of the rice paddy. 　The seal was something Jimbei had never seen before. So he took it to an art dealer in Fukuoka where his elder brother once worked. Since the seal glittered and was heavy, the dealer thought it was pure gold and advised Jimbei to melt it down and make ornaments for armors.
　However, Kamei Nammei, a Confucian scholar and a friend of the dealer saw the seal and the inscription of five Chinese characters,　漢委奴国王, 'Kann no Wa no Kokuou' (the national head of the Kann's state of Wa) remembered the passage in the Hann's History Book.
　The scholar felt sure this seal was the seal the Chinese emperor gave to the delegates of Wa. Suddenly the seal became the talk of the town. Then the village headman Musashi made a report to the county office together with Jimbei's statement.
　The scholar wanted to have the seal as his own treasure and offered 15 ryo (highest monetary unit then) to the county office to buy it, but his request was turned down. So he raised his offer to 100 ryo. The officials were quite surprised at this and made a report to the administration office of the provincial ruler Kuroda, along with the owner's statement.
　The provincial government appointed the Confucian scholar and several professors at the Shuyukan Provincial School to undertake research on the seal. The government gave Jimbei 5 white gold pieces for the seal and took possession of the seal. Since then, the seal was maintained as a treasure of the Kuroda clan.
　The seal was designated as a national treasure in the Meiji era and re-designated as a first-class national treasure in Showa 29th year (1954) and was kept at the National Museum in Tokyo. Later the seal was donated by the Kuroda family to Fukuoka city. With the opening of the Municipal Museum, the seal is now on exhibit at the Kuroda Memorial Room in the museum.