As a result, his legitimate son, Hirofusa, was killed in a battle at Saijo in Aki Province in 1385, and Motoharu had Hirofusa's son, Mitsufusa MORI, succeed to own position, and acted as guardian until Mitsufusa grew up.
1385年に嫡子広房が安芸西条にて戦死するに及び、その子毛利光房に跡を継がせ、その成長まで後見することとなる。