Amago clan
Along with the family troubles concerning succession, Motonari and Amago Tsunehisa gradually grew hostile towards one another. In March, 1525 Motonari and several other local lords decided to change allegiance to Ōuchi Yoshioki. In June, Yoshioki sent his army to Kagamiyama Castle and took it from the Amago clan. Considering Kagamiyama's weak defenses on a low hill, Yoshioki built a new castle called Tsuchiyama Castle at the western edge of Saijo Basin on a high mountain and demolished Kagamiyama.