Joso Tenmangu was founded around 1400 during the Ōei period, as the Tenman faith—born from reverence for Sugawara no Michizane after his death—spread across the Kantō region. The shrine's crest features the plum blossom, the flower Michizane cherished. As terakoya schools flourished in the thriving merchant town of Mizukaido during the Edo period, devotion to Michizane as the patron of learning deepened among educators and families alike.