Naomasa disliked the residential castle of Mitsunari ISHIDA who was a rebel general, and planned a construction of new castle at Isoyama at the lakefront of Lake Biwa, but died of war injury in 1602 before starting the construction.
直政は賊将・石田三成の居城を嫌い、琵琶湖の湖岸の磯山に新城建設を計画したが、建設に着手する前に戦傷が元で慶長7年（1602年）に死去した。