They planned to overthrow the Tokugawa Shogunate by attacking and setting fire to Yokohama Foreign Settlement, thereby stirring up the spirit of Sonno joi, but this secret plan became known by the Tokuwa Shogunate.
横浜外国人居留地を焼き討ちし、尊王攘夷の精神を鼓舞し、倒幕の計画をたてたが、この密計が幕府の知るところとなる。