When the Battle of Hoji occurred in 1247, Suemitsu was on Yasumura MIURA's side and committed suicide with the Miura family at Hokke-do which was the private Buddha statue hall for MINAMOTO no Yoritomo.
1247年の宝治合戦で三浦泰村に味方して三浦一族とともに源頼朝持仏堂であった法華堂で自害する。