Rai San’yo was a leading Japanese historian, poet, and writer in the late Edo period. He was also well versed in art and worked actively in various fields. In 1818, during his journey in western Japan, after visiting Mogi via Nagasaki, it is said that he visited Shibue Ryuen, the Confucian, who had a private school in the castle town in Tomioka. While viewing the Amakusa-nada sea, he wrote the poem “Amakusa-nada ni hakusu.”
His original handwriting is shown in the photo plate on the surface of the monument.