In 1331, Emperor Godaigo, whose plan to overthrow the Kamakura bakufu (Japanese feudal government headed by a shogun) was revealed, went to Mt. Kasagi, with Sanshu no Jingi (Three Imperial Regalia), raising his army and staying there, which lead to Genko War.
1331年に鎌倉幕府の倒幕計画が発覚した後醍醐天皇は三種の神器を保持して笠置山にて挙兵、篭城して元弘の乱の発端となった。